열쇠 vs 키: Which is more commonly used?
I recently learnt 열쇠 that means keys. But in some cases, 키 is also used.
Which is more common, or when is one more naturally used over the other?
out of 열쇠 and 키, what is more naturally spoken, or are they both equally used?
eg. 차 키
vs
차 열쇠

Question

열쇠 vs 키: Which is more commonly used?
I recently learnt 열쇠 that means keys. But in some cases, 키 is also used. 
Which is more common, or when is one more naturally used over the other? 
out of 열쇠 and 키, what is more naturally spoken, or are they both equally used?
eg. 차 키 
vs
차 열쇠

Answer

Hahaha that's interesting. At first I thought they are both used commonly and it didn't matter which one to use but I saw your examples and realized there is a subtle difference. Cuz we say 차 키 and 집 열쇠. I mean it's fine if you say 차 열쇠 and 집 키 but it just doesn't sound as natural.