The ruy lopez is played twice as often as the italian game. Why? I don't see a big difference between e4 e5 Nf3 Nc6 Bc4 and e4 e5 Nf3 Nc6 Bb5 a6 Ba4 b5 Bb3. Yet clearly white must be better in the second line, because the ruy is much more common and black almost never plays 4... b5.

Why is the second position considered better than the first? The only differences are that in the ruy the pawns are on a6 and b5 and the white bishop is on the a4-d1 diagonal instead of the a6-f1 diagonal.  How do these differences give white a better position?

The Spanish gives white a +/= advantage and with Bc4 the best White gets is equality.

That is why.

The Norwegian Defense (shown in your last diagram) is know to be very good for White despite being popular among patzers with the Black pieces.

Closed Ruy Lopez and Giuoco Piano (common Italian line) feel pretty similar to me as White. The Bishop eventually gets chased to c2. White develops and works to support a pawn push to d4. Both are pretty slow to get going.

For club players, the Italian is a lot more exciting. The Bishop on c4 aims at the vulnerable f7. If Black plays the Two Knights Defense, there can be a lot of fireworks. See the Fried Liver Attack, Lolli, and Wilkes-Barre/Traxler.

A big difference is that the bishop is a lot safer on b3 - if black plays ...d5, the bishop isn't attacked, if black plays Na5 it is attacked but not hanging. That can mean an important tempo in many lines coming from the normal Two Knights.

thanks guys, i was looking at the position more in terms of what diagonal, and thus what it can do in the future, the bishop was on rather than how safe it was on the actual square atm. till now i'd just heard that the ruy was more advantageous for white without any explanation, thanks again

Out of interest, is there an actual reason why the norwegian defense is inferior?  I usually just let it transpose into a regular closed ruy.  Am I missing something?  (Either I am missing something fairly big, or "known to be very good for white" is a bit rash).  I think I tried something else once and wasnt really very happy with whatever move I made after I'd made it. 

hmm ok well that makes sense, but what I really meant was just the position in the diagram.  what r&o referred to as the norwegian defense.  Is there anything good for white there if black just plays Nf6 say?

Diagram 2 is better because whites bishop on b3 is safer than compared to c4 when there is a threat of d5. Also blacks pawn advances on the queen side are weakening and can be targeted with a4 etc. Not to mention the weak square on c5.

The most common move in the Ruy is not to rush b5 after a6, but to play nf6 and still keep b5 an option. Like in the closed and open Ruy Lopez systems.

Also the Italian and Ruy have completley different ideas despite the slight difference. Ruy Lopez targets the e5 pawn, by having the looming threat of grabbing the knight on c6 and then taking the pawn on e5. (not immediatley because Qd5 wins back the pawn with an advantage). Where as the Italian game whites guns are aimed at the f7 pawn, creating many threats with ng5.

Hope this helps.

Well here is one difference between the two positions. don't pay attention to the first caption.

I thought the difference was that the pressure created by Bb5 generally forces black to play ...a6 and eventually ...b5 weakening the queenside. This gives white enough time to play c3 and d4 I guess, because in the Italian white is just unable to do this and I'm not exactly sure why. The move ...Bc5 in the ruy is considered inferior to the placement at e7 because d4 kicks the bishop, but in the italian this can be safely played because white can't play c3 and d4 in that line without major drawbacks.

This is better for White

Than this:

The giuco piano pawns are pure potential, still ready to meet whatever White brings... flexible.. But those Black queenside pawns in the Ruy are committed and not optimal. White has something to work with there.

I think it's  mainly because white can set up his two pawn center. Sometimes that queenside structure for black can become useful if white is compelled to advance d5. Then if black played ...c5, he can continue with ...c4 with some play on the queenside, though just as often white can play a4. But the pawns do have some potential in the closed centers which tends to happen in the closed ruy lopez. But in the open if he has pawns like that than they are almost certainly inferior unless black can trap white's bishop. Another theory could be that white can develop more quickly by castling after black's ...Nf6. If black plays ...Nxe4, white responds with d4 and wins the pawn back and now black had to give up his e pawn, though it is pretty sharp but it favors white. So then black plays ...Be7 allowing white to eventually play d4. Whatever the true difference between the ruy and italian is, it is very subtle yet important because in the ruy white actually achieves his strategic goal, which will probably give him slight edge.