thin out vs trim down

thin out and trim down both are verbs.

Word	Noun	Adjective	Verb	Adverb
thin out	No	No	Yes	No
trim down	No	No	Yes	No

As verbs, trim down is a hypernym of thin out; that is, trim down is a word with a broader meaning than thin out:

Other hypernyms of thin out include bring down, cut, cut back, cut down, reduce, trim, trim back.

thin out (verb)	trim down (verb)
make sparse	cut down on; make a reduction in
become sparser
lessen the strength or flavor of a solution or mixture