Hello

Can someone plz help me understand the difference. I understand that on the GMAT, "if" is used for a conditional idea, while "whether" is used for an alternative or possibility. But to me both seems the same thing!

e.g.

* If I go to xyz fast food I will eat burger.
* I have not decided yet whether i should go to xyz fast food to eat burger.

Both of the statements provide a condition here. So when to use if and when to use whether?

thanks