well,.. never mind them at this time. actually Some of them sound the same. so we may know what does that mean from other words before them and after them in a sentence. hope it may help you... 즐!

It is difficult to find out the difference among some letters when you listen to every single letter one by one.I think I had the same feeling with you at the beginning of learning alphabet,but in your later study,you will find it less diffcult to figure it out when listen to the sentenses or words ,at the same time ,pay attention to the difference among pronunciations of the letteres you want to tell.In all,the more you listen,the easier you can tell the difference in the similary pronunciations.This is my experience and I hope it is helpful for you.

The most difficult sound I have trouble with is 오(o) and 어(eo) 오 is like ohhhhhhhhhhhhh o 어 is like uhhhhhhhhhhhhh but if you listen really really really carefully it can sound like e-o. That's my opinion. I could be hearing things.

From one learner to another, all I can say is listen... over and over and over ~~~ Haha. Hopefully someone else will give you another way, but just try to find listening exercises that focus on the letters that are difficult.