There's not difference on meaning. For example:"I like brown bag" 나는 갈색 가방을 좋아한다 : emphasis on "(like) brown bag" 내가 갈색 가방을 좋아한다 : emphasis on "I" Both are same meaning. More example. "I ate candy" 저는 사탕을 먹었어요. : focus on "candy" 제가 사탕을 먹었어요. : focus on "I" (Both used the honorific) "Who ate my candy?" 누가 내 사탕 먹었어? (non-honorific) "I ate it." (honorific) 제가 먹었어요. : Correct 제가 사탕을 먹었어요 : Correct 저는 먹었어요 : Strange 저는 사탕을 먹었어요 : Still strange Because he wanna know "WHO ate that", not "candy". but "I didn't eat that but John ate it." 저는 안 먹었는데 John은 먹었어요 : Correct 저는 안 먹었는데 John이 먹었어요 : Correct, more focus on snitching than before 제가 안 먹었는데 John은 먹었어요 : Correct, and more focus on "I'm better than John" 제가 안 먹었는데 John이 먹었어요 : Correct