I'm a chessplayer, and except for some social and online (casual) poker, I don't have much experience. But my impression of real (i.e., not online) poker is that you attempt to understand the playing style of other players (aggressive? bluffing a lot? easily intimidated?), and to make rapid decisions under stress and uncertainty that take into account not only the odds of hands but the style of the other players. Perhaps this is happening under the level of consciousness (since it's usually so fast compared to chess).
As far as I know, von Neumann was the first to come out with some results for 2-person poker. One of which was the seemingly counterintuitive result that when you bluff, do it with completely garbage hands.
If you're a chess player then I think you'd appreciate the more scientific and acedemic aspects that go into developing poker strategy. You know of IBM and Deep Blue I'll assume.
A team, I think out of Canada, built a program that can play HU LHE (heads up limit holdem) almost perfectly. HU LHE is about the simplest form of poker there is that is played nowadays where there are only two players and each bet is limited to one amount so it's a game that is easiest to quantify. It's sort of a Deep Blue for poker, but at the very simplest form of poker.
When you expand to a table of 6 or 9 players and make the game no limit where you can bet any amount you want, the game rapidly gets more complex and thus harder to "solve"...or more difficult to program a computer to play, and beat, human players.
This is still talking about holdem where each player gets two cards. I play Pot limit Omaha where each player is dealt four cards,...growing in populartiy as holdem players get more proficient and the game gets more "efficient"....which adds another layer of complexity.
You are partly right but really overlooking (I think at least) a big portion of poker theory.
First of all, online poker is "real" poker. It's not the traditional way it was played but it's poker none the less and is where most of the action nowadays is (see pokerstars with 100k people playing anytime of day).
Claiming online poker isn't real poker is akin to claiming that only pit traders are real traders (i.e., not screen traders).
Much like transition of trading has gone from pit trading to screen trading and to automated/HFT/Black box trading now...so has poker gone from live play to online play...and could eventaully get to programmed play as the game gets more "solved".
The best players in the world 50 years ago were old road gamblers that just had experience. As math teachers and more acedemic players looked at the game they basically ate the lunch of a lot of the "old guard". Today, with the advent and growth of online play, now the best players in the world are young kids that sit at home and can play 100 hands an hour...per table...and can play 12 tables at a time. They can see 1,200 hands an hour without leaving your house. For comparison, a player in a casino might see 30 hands an hour. This is what I meant by the learning curve. I have played more hands of poker...and could argue....that I have more experience than a player that has played in a casino for 50 years. I've played over a million hands of poker...he has not.
Sorry for the rant.
With that said....back to topic. The reason the online players are so much better is because they developed better fundemantals of the game. They don't prey on drunk tourists coming to a casino playing badly and spewing chips...online players have to play and win against other online players.
So they analyze there game more, create and develop tools for analyzing play (see Holdem manager and poker tracker). Develop equity calculators to run simulations of a hand vs a range of hands (see propokertools.com).
So when you say playing style, your partly right but it's not so simple as he is bluffing a lot. Its more along the lines of...he is playing 50% of his hands but only raising 10%. We can assume he is a rational player so probably playing about the best 50% (AA,KK,AK,QQ etc) of hands and folding the worse 50% (23, 24, 72, 83 etc) of hands. Of that top 50% of hands (about 85 distinct hand) he is likely raising the best 10% of those hands (AA, KK, AK, QQ) and limping in the bottom 40% (K9,Q9, JT, J9, 9T). So when this player limps in or raises preflop, you can run this likely range of hands vs your hand to try and deduce the best course of action (raise,call or fold) and go from there.
I'll stop there but that literally just scratches the surface of thought that can go into making one decision in the game. The best players in the world use to just think in terms of "he plays alot of hands so he is aggressive". Or "A player bets a lot so he must be bluffing a lot". But the information and analysis that goes into the game nowadays has gotten much more refined than that. And if you want to win at the game in the long run, you'll need to stay competitive on how you approach the game and make your decisions.