filter vs separate out

filter is a noun but separate out is not a noun.

Word	Noun	Adjective	Verb	Adverb
filter	Yes	No	Yes	No
separate out	No	No	Yes	No

As verbs, filter and separate out are synonyms defined as:

Other synonyms of filter include filter out, filtrate, strain.

filter (noun)	separate out (noun)
device that removes something from whatever passes through it
an electrical device that alters the frequency spectrum of signals passing through it

filter (verb)	separate out (verb)
remove by passing through a filter	remove by passing through a filter
pass through
run or flow slowly, as in drops or in an unsteady stream