Slav or Semi-Slav Defence?

When does the Slav and when does the SemiSlav occur?At Wikipedia it says that SemiSlav is QGD variation(e6) but in many Slav games I see the e6 move being played in the opening...so I am kinda confused...I would really appreciate any help about this mixup and if someone could point out the difference between the two(mainly around the e6 move)Thanks in advance!

The Semi-Slav 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6, 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Nc3 c6, or 1. d4 d5 2. c4 c6 3. Nf3 e6 4. Nc3 Nf6. The Semi-Slav does not arise until Black has made his fourth move.

The Mainline Slav 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 dxc4. The Slav also gets most of the lines that occure after 1. d4 d5 2. c4 c6, which includes the a6 systems.

The Cambridge Springs variation is also hard to pigionhole. 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7 5. Nf3 c6 6. e3 Qa5 or 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 Nbd7 6. e3 Qa5. It is just as much a Semi-Slav as it is a QGD.

In slave light square bishop is out.

In semi slave it is in behind e pawn.

love.

anything else?

aggressivesociopath was spot on.

There is a transposition in the Soultanbeieff:

Slav 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3 dxc4 5 a4 e6 6 Bg5

Semi-Slav 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3 e6 5 Bg5 dxc4 6 a4

The Slav is c6 is played.

The Semi Slav c6 and e6 is played that is the difference.

I know that..the thing is that for example after Bf4 e6 it is called Slav but if Bishop is closed in it is a Semi Slav(ilgambittoo 's post) but but I do not think they become different openings because of this...

Sounds confusing the way you put it.

c6 The Slav

just e6 more likely QGD

c6 and e6 is the slav and the QGD combined making it the Semi Slav

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It is just that simple.

f5 can block the bishop in that would not make it the Semi Slav.

See in the Semi Slav

black can play e6 then c6 or c6 then e6.

It has to develop to the Semi Slav it can go by route of e6 (QGD) and c6

or by route of c6(Slav) and e6 to become the Semi Slav.

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The Slav is just c6 without e6. Which means g6 > Bg7 will be played so black can castle.

I have seen d5 c6 Nf6 (Be7 I think) Bf5 e6 and it was called a Slav...

This is the Semi-Slav:

If Black plays c6 and does not reach this position, or one derived from this position then he is playing the Slav:

I know it is weird, but the Semi-Slav does not arise until Black has made his 4th move. The Semi-Slav is not an entire answer to the Queen's Gambit because Black still has to prepare for his choice of the Exchange Slav or Exchange Queen's Gambit Decline.

Again if e6 is a move by black if can not be the Slav.

Where ever you seen this it was wrong.

Depending on White's moves in the situation on the board?

And If your opponent does not have the skills to exploit it in time then your ok.

If Black plays Bf5 before e6 it is NOT a Semi-Slav. That is the main defining difference.