But i honestly saw hard any difference for a reason to play a second time, unlike Kotor, had 2 completely different endings, which made it worth it.
Well not only are there different endings but different events by making a different choice in about every part of the game.
-You can fight Saren a second time or make him commit suicide
-You can kill Wrex or keep him
-You can pick Ashley or Kaiden to die on Virmire, in different locations too
-You can save the council or not
-You can pick Udina to be in the council or Anderson
-You can have sex with Ashley or the alien chick
-You can kill the woman on Virmire you find in the lab or let her live
-You can kill the alien on Feros or let her live
-You can kill the rachni queen or let her go
etc.