1. 에 and
Although they are different from each other, they sound almost the same practically.
We do not differentiate them that much.
2. 어 and 오
They are definitely different from each other.
Think about an English word 'or'.
Though 'r' is a consonant, it sounds to me '어' in Korean.
When I hear the word 'or', I could transliterate it as '오어' in Korean.
Listen and practice 오/어 everyday.
에 and 애 are homophones. They are not pronounced any different. Trust me.
You use 에 after a location so like 학교에 means "at school" while
애 is used for everything else. That is the general guideline when you need to use 애 or 에.
As for 어 and 오. You tend to hear 어 in the middle of the sentence and 오 is typically at the end of the sentence.
These are not homophones.
어 is uh
오 is oh
This is what my teacher told me, and it worked for me. In fact, it worked for everyone I know.
에 = E as in BED
애 = A as in BAD.
In reality, native Koreans will not know difference - at least not consciously. When the time came, I saw that every single native Koreans cold tell the difference. So if someone say they are exactly the same, don't believe them.
어 = Awww
오 = Ohhhh.
That's all you need to know.
In reality, Koreans will get lazy and may not pronounce these vowels precisely. We learn to recognize these "accents" as we become more proficient. You need not to worry about it now if what you are studying now is Hangul.
When I say OR slowly, during the O my jaw is dropped and the sound is coming from the front of my mouth just behind my lips. This is the same with 오.
When I get to the end of OR to the R sound my jaw halfway closes and the sound moves back to the back of the mouth and into the throat. Now, keeping your jaw halfway closed and making the sound come from your throat not your mouth, think of the U in the word sun. Try that for 어
