Hehe, you have questions? Allow me to deliver some answers:
Phantasy Star Online: Blue Burst is a new version of Episodes I & II, and only available on the PC. It includes many new features over the older PC version of PSO and the console versions of PSO such as server-side saving (To reduce cheating and hacking within the game), Team Games, New Quests, and allows for Expansion Packs to be brought out such as Episode IV.
For more information, click here.
Phantasy Star Universe is a continuation from the old SEGA Megadrive Phantasy Star series of games. This is basically a different adventure then that of Phantasy Star Online games. This is
NOT PSO, Episode V, or a part of the PSO series, this is a completely different series, continuing the story from the SEGA Megadrive games. Just wanted to make that clear
In Phantasy Star Universe, the game is centered around the offline game and takes place in a similiar environment to those of the old PS games where you basically explore, fight, discover, etc. much like a true RPG game, different to PSO's RPG play where you dont unlock levels, you instead discover more of it! In the online game, you basically expand the offline game a lot more, being able to play with friends aswell.
For more information, click here.