"항상"means "often" "언제나"means "always"

wow, xtinee, you are such a good korean speaker! your question is always 항상 어렵다... ㅠㅠ your question are 언제나 어렵다! my answer is, totally the same meaning. but if try, 항상 : always 언제나 : all the time Adding : often : 자주 자주 is often, it's like almost. like 80% but not 100% or 99%. 항상, 언제나 are almost 100%, or 99.9999%. that's 항상 or 언제나. always or whenever all the time. hope it helps

The words "항상" and "언제나" can be used interchangeably. For your reference, 항상 is Sino-Korean and 언제나 is pure Korean vocabulary.