Korean:subtle difference between 이 / 가 and 은/는, please help?

Question

I would like to the subtle difference between this two particle. thanks

Answer 1

All four are subject particles.  I think the main difference between the two sets is that 이 and 가 put more emphasis on the subject and 은 and 는 put more emphasis on the action.

Also, 가 and 는 are used after words that don't end in consonants and 이 and 은 are used after words that do.

Answer 2

it's very easy

example: 내가 and (친구)들이

whenvever there is a 바침 like 들 --anything that has more than one consonant [in this case: ㄷ and ㄹ]

if there isn't any then you use 이

same with 은 and 는

example: 나는 and (친구)들은

if there is only one consonant (ㄴ) then you put 는 after it

if there is more than one consonant (ㄷ and ㄹ) than you use 은.