Answer:
Passing an amendment is when you get it approved by congress and it has to be voted and legislatures from other states need to approve it also.
In order to pass a law you have to have a bill that gets to both houses and congress has to vote on it then when congress does this ( if they decide its okay) they pass it on to the president. If your president signs this bill, it officially becomes the law.
Explanation:
So the difference is that passing an amendment doesn't really need to get approval from the president as it does more of passing a law. He doesn't have a role in that part.