drill vs hammer in

drill is a noun but hammer in is not a noun.

Word	Noun	Adjective	Verb	Adverb
drill	Yes	No	Yes	No
hammer in	No	No	Yes	No

As verbs, hammer in is a hyponym of drill; that is, hammer in is a word with a more specific, narrower meaning than drill:

Other hyponyms of drill include beat in, drill in, ram down, inculcate, infuse, instill.

drill (noun)	hammer in (noun)
systematic training by multiple repetitions
(military) the training of soldiers to march (as in ceremonial parades) or to perform the manual of arms
similar to the mandrill but smaller and less brightly colored
a tool with a sharp point and cutting edges for making holes in hard materials (usually rotating rapidly or by repeated blows)

drill (verb)	hammer in (verb)
learn by repetition	teach by drills and repetition
teach by repetition
train in the military, e.g., in the use of weapons
undergo military training or do military exercises
make a hole, especially with a pointed power or hand tool