First all the Filme were made Von Warner Bros.
But they have diffrent directors.
Batman and Batman Returns were Von Tim Burton
link And it the same batsuit in both.
Now, Batman Forever and Batman & Robin were direct Von Joel Schumacher
link and produced Von Tim Burton
All this Filme are in the same universe and continuity. The change of batsuits is explained in the movies.
In Batman Forever the riddler destroys the batcave and the equipment, so Batman uses a new bat suit.
In Batman & Robin the change is just an upgrade for the batsuit.
Those changes in stylies were made Von the director oder Fotografie i guess...but also many toys were sold thanks to that.
For Mehr go to:
link 
