에 - 애
예 - 얘왜 - 웨 - 외
The truth is, even Koreans have trouble differentiating them. Some say they do, but it is close enough that it becomes waste of time to learn how to pronounce them correctly.
Don't worry. Everybody knows it is so close, so when you say something Koreans will rely on the context to get what you mean, rather than your pronunciation. Here are some talks among Koreans saying "I can't differentiate them. Can you?" (Sorry, discussion is all in Korean. :) )