why does the world of twin-sun in LBA 2 seem so different compared to the first game? also what other things changed from the first game to the second one?

Different? I always thought that they did a great job at re-making Citadel Island in the second game :) keep in mind that the largest portion of LBA 2 is not played on Twinsun ;)

I like the first game better btw, but that's cause I think the story is way better and less cliché, both games are brilliant though :)

Outdoors view changed to 3D with graphical effects, such as rain. They should've kept it original, if you ask me.