서 vs. -은 후에
돈을 모은 후에 뭐할 거예요?
돈을 모아서 뭐할거예요?

As ive learned, these can both mean "after saving money, what will you do?"

Is there just a difference in nuance? or is one better than the other? or is there no difference at all?

Question

서 vs. -은 후에
돈을 모은 후에 뭐할 거예요? 
돈을 모아서 뭐할거예요?

As ive learned, these can both mean "after saving money, what will you do?"

Is there just a difference in nuance? or is one better than the other? or is there no difference at all?

Answer

There are a bit of difference between them in nuance.

돈을 모아서 (그 돈으로) 뭐 할 거예요?
By saving money, (And then) what  are you going to do (with that money)?

돈을 모은 후에 뭘 할 거예요?
After saving money, what will you do?

Answer

No difference, but the second one is more common in everyday Korean.:)

\^o^/