They both mean "all". The biggest difference is in their usage. 전부 is a noun and adverb, but not adjective. 모든 is an adjective only. 모두 is a noun/adverb form related to 모든 and is much like 전부 in meaning. 전부(全部) originates from 한자(Chinese character), so sometimes works better in more formal and scholarly expressions. So the two's role in a sentence is quite different. ex) 나의 모든 것: All that is mine; All that is part of me; My all. 나의 모든: bad expression! - needs a noun. 나의 전부: My all. 나의 모두: My all. 재산(의) 전부를 대학의 장학금으로 내놓다: Donated all of his wealth to college scholarship. 모든 재산을 대학의 장학금으로 내놓다: Donated all his wealth to college scholarship. 재산을 전부 대학의 장학금으로 내놓다: (same - "donated his wealth completely") 재산을 모두 대학의 장학금으로 내놓다: (same)

Strictly speaking, your question is not correct. The following question is correct. What is the difference between 모두 and 전부 ? since both of them mean "Everything". 모든 means "all, every, whole, entire" it is a determiner and used before a noun. ex) 모든 사람 = everyone 모든 것 = everything 모든 진실 = whole truth 모두 means 1. all, everyone, everybody (NOUN) 2. all, altogether, all together, in all (ADVERB) 전부 means 1. the whole, everything (NOUN) 2. all, altogether, all together, in all (ADVERB) If 모두 and 전부 are used as an adverb, they can be replaced with each other. But, if 모두 is used as a noun, it usually comes to the people. ex) 그의 말은 전부 거짓말이다 = 그의 말은 모두 거짓말이다 Everything he says is a lie 나는 그 작가의 소설을 전부 읽었다 = 나는 그 작가의 소설을 모두 읽었다 I've read every novel that writer's ever written. 모두가 고개를 숙였다 Everyone lowered their heads 가족 모두가 여행을 떠났다 The whole family left on a trip.