Obi-Wan = Soresu, Anakin = Djem So.
The saber fights in the Prequels were supposed to tell the story, at the end of ROTS Anakin is now extremely aggressive with Obi-Wan being on the extremely defensive side of the coin.
Some background on why we have saber forms:
"When the Star Wars prequel trilogy began filming, Peter Diamond was replaced by Nick Gillard, who completely rethought the Jedi fighting styles. George Lucas envisioned that during this time period, the Jedi had reached their peak in terms of martial arts development, so the choreography had to be a great deal faster and more sophisticated.[89] Gillard wanted to convey the sense that the Jedi had studied every single style of swordplay available, his idea being that since they had chosen such a short-range weapon, they would have to be so good if they're up against ray guns and lasers. Gillard choreographed the duels as what he described as "a chessgame played at a thousand miles an hour", with every move being analogous to a check. Aiding Gillard was the martial artist Ray Park, who portrayed Darth Maul, and helped train Liam Neeson and Ewan McGregor."
"The seven forms of lightsaber combat received their first description and elaboration in the Fightsaber: Jedi Lightsaber Combat article released in Star Wars Insider 62. While these fighting styles would be mentioned and used in Star Wars: Knights of the Old Republic II: The Sith Lords, Star Wars: Jedi Knight II: Jedi Outcast and its sequel, Jedi Academy would instead use the three styles; Fast, Medium, and Strong. While each of these forms had strong parallels to the Three Rings of Defense described in the 1998 expanded universe novel I, Jedi, they may be little more than game mechanics."
Wookieepedia:
http://starwars.wikia.com/wiki/Lightsaber_combat
