1.d4 e6!? ... have you ever seen this variation?

1.e4 e6 2.d4 d5 3.e5

Black is playing the French Defence

White is playing the Advanced Variation

Now when you ask what are they both playing? People respond with?

They are playing the French Defence, Advanced Variation.

It is a combination of what both sides are playing.

"White doesn't have to play 3. d5"

Yes, white does have the option to transpose into something where he gets much less advantage. He almost always has this option though.

"How can you say c5 is weaker than d5 if white gets space advantage either way."

Black achieves more counterplay against the weak d4 pawn in the advance. He plays thematic moves like Qb6, Nc6, Nge7 (or Nh6) to f5, and f6, and takes down white's center. In the Franco-Benoni, black just gets a worse position. It's not clear what black can do actively if white plays against the b5 push and holds his center well.

Are you sure about that statement I highlighted in blue?

1.d4 e6 2.e4 c5

 White is playing the Queens Pawn Opening

 Black's is playing the Franco-Sicilian Defence

Together they are playing the ECO C00 Queens Pawn Opening, Franco-Sicilian Defence

After 3.d5

by white the position begins to enter Benoni type of position's which are Queen Pawn Opening's. So yes the position are still under the Queen Pawn Umbrella becuase their are still Queen Pawn lines which can be played.

The above move I played was a typo I was trying to write what that guy was saying but his text was small lol.

1.d4 e6 2.e4 b6 3.Nd2 d5

 White position is Undefined

 Black's position is Undefined

Didn't try to put 2 d5 move's in lol my bad

This is almost all false, but I'm going to do the wise thing and stop arguing with you because you seem dead-set on perpetuating faulty ideas about transpositions. Maybe another player who understands could help you- I'm done with this particular debate for now.

Thank you I'm glad we are in complete agreement.

The reason why they do naming of variations is so its easy to refer to. Now lets follow the train of logic here. An see how complicated it would be if we choice to do it the other way. Watch.

1.d4 e6      (is not a French)

White is playing the Queens Pawn Opening

Black's position is Undefined becuase you can't call it a French unless white is playing a Kings Pawn Opening.

1.d4 e6 2. e4

White is playing the Queens Pawn opening

Black's position is Undefined

1.d4 e6 2.e4 d5

White is no longer considered to be playing a Queens Pawn Opening any more becuase no Queen Pawn's Openings can arise from the following moves any longer. It has moved to the realm of Kings pawn Opening.

Black is now playing French Defence Main Line

1.d4 e6 2.e4 d5 3.Nd2

White is playing the Tarrach

Black is playing the French Defence

^^ This is how it normally goes

Notice how simple it is:

The game started with a Queen Pawn opening it than transposed into a French Defence, Tarrasch Variation

Now watch what happens if we change the move's.

1.d4 e6      (is not a French)

White is playing the Queens Pawn Opening

Black's position is Undefined becuase you can't call it a French unless white is playing a Kings Pawn Opening.

1.d4 e6 2. e4

White is playing the Queens Pawn opening

Black's position is Undefined

1.d4 e6 2.e4 a6 3.c4

White is no longer considered to be playing a Queens Pawn Opening any more becuase no Queen Pawn's Openings can arise from the following moves any longer. It has moved to the realm of Kings pawn Opening.

White is playing the New St. George Three Pawn Attack

Black's is playing the St. George Defense

^^ This is how it normally goes

Notice how simple it is:

The game started with a Queen Pawn opening it than transposed into a St.George Defence, New St. George Three Pawn Attack

Now watch what happens if we apply your logic to the position's.With your recommendations on what you believe should be labeled the French.

1.d4 e6      (is not a French)

White is playing the Queens Pawn Opening

Black's position is Undefined

1.d4 e6 2. e4

White is playing the Queens Pawn opening

Black is playing the French Defence

1.d4 e6 2.e4 a6 3.c4

White is playing the New St. George Three Pawn Attack

Black's is playing the St. George Defense

^^ Notice the change now.

The game started with a Queen Pawn opening it than transposed into a French Defence it than tranposed into a St.George Defence, New St. George Three Pawn Attack

Now just tell me don't you think its more complicated telling someone the line transposed 100 time's.

He's actually a joke dpnorman, so are several others going around this site (and particularly this board) who talk authoritatively and give advice acting like they're doing analysis and can tell people things. 

I've seen one guy going around giving "recommendations" and suggestions for opening repertoires who stated that c5 and Qa5 were hardly ever played or relevant in the King's Indian Defence....c5 ever, at any point. It wasn't some strange wording or anything like that, that's exactly what he said and he confirmed it again after I questioned it. And he wasn't obviously ridiculous like some of these other people. He was bringing up all sorts of things about good bishops or squares, mostly all nonsense, talking about how you should play f3 in such and such a position (obviously something he read himself recently).... it's like he was emulating a good chess expert analyst in every possible way... the only difference being the actual skill and he didn't have a clue what he was talking about.  

Many hobbies or interests you can start to talk authoratively and confidently after a while. It doesn't work that way except for a small minority of people in chess. I'll make some cautious comments every now and again but I'm prepared to sit back and listen to someone good who clearly knows much more than me. The rating should be some clue if you're no good. 

Basically the last people you should ever take serious analysis from are the people here, no matter what rating you are. 

It's true yu need to be cautious about free advise, because you tend to get what you pay for.

GM's have written books on how black can build a repetitoire around playing 1...e6, against 1.d4 or 1.e4. In my opinion a particularly good one is Eingorn's "A rock solid chess repetitiore for black".  Of course the french defense is a key part of that repetitiore.  It doesn't seem hard to understand that when you are playing white, and say choose to play 1.d4, you are not in charge of how your opponents choose to build their repetitoire. So using "logic" to try to "proof" 1.d4 e6 doesn't have the right to exist is a waste of everyone's time. Would suggest that if your results using the Tarrasch against the French are so blindingly good that you think about playing 1.e4, rather than 1.d4. Whatever the elite players like Carlsen, Anand, or Kramnik may think about the french defence, in fact they have all played some games with it, your opponents are not remotely at that level. In clubplayer chess the french is extremely popular defense to 1e4. 

Eingorn has also written a book "Creative Chess Opening Preparation" were in one chapter explains his thinking and conceptal ideas behind playing 1.d4 e6 2c4 Bb4ch 3Bd2 a5. In other chapter's, his ideas behind playing h6 in the french, particularly against the Tarrasch. For strong players this sort of conceptal thinking is important. On the other hand, in vote chess games tend see a lot of talk about being flexible with "choices", and trying to "proof" best sequences of moves from move one using statistical database information. In the worse cases the players promoting these ideas are really weak players using software later in game to find strong moves to boost their reputation. In best cases players with a misguided view on how to play the opening in coorespondense chess, at least in my opinion.

1.d4 e6: we are within the transposition realm

If white plays 2.d4 -> f5 and we are going into a Dutch, or 2...Nf6 and this can become a QID, a Nimzo or Bogo Indian, or even transpose in a QGR.

If 2.e4 -> d5 and this is a French.

If other, Black still has ways to transpose sooner or later.

It is just my opinion, though.