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Какого типа эта машина? (concrete)
Что это за машина? (very general)


Который час?
("Which hour is it?")
Remember this phrase, this is only grammatically safe way to ask what time is it. :) ...

"какой" normally refers to an adjective in a normal form.
"каков" normally refers to an adjective in a short form.

Short form adjectives (as well as "каков") in contemporary Russian are rare,...

Yes, good explanation.

каков, какой makes a question to an adjective, while что makes a question to a noun.