한국어, 한국말 is same meaning, but the slight difference is that: 어, which can be written in the Chinese character 語, means “language”, and 말, which is a native Korean word, also means “language”. So basically 한국어 and 한국말 are the same meaning, but 한국어 is a little more formal word while 한국말 is a more colloquial word. 예: 1.저는 한국어를 공부합니다 2. When a Korean nativer speaker hear a foreigner speaking Korean and a Koren person says: 와, 한국말을 잘하시네요 (correct) 와, 한국어를 잘하시네요 (not natural) Hope it can do help

한국어 와 한국말의 차이는 없어요. ^^ 다만, 한국인들은 다른 언어와 비교 할때 "한국어"라는 말을 많이 써요. ^^