following vs trailing

following and trailing both are nouns.

Word	Noun	Adjective	Verb	Adverb
following	Yes	Yes	No	No
trailing	Yes	No	No	No

As nouns, trailing is a hyponym of following; that is, trailing is a word with a more specific, narrower meaning than following:

following: the act of pursuing in an effort to overtake or capture
trailing: the pursuit (of a person or animal) by following tracks or marks they left behind

Other hyponyms of following include tracking, shadowing, tailing, stalk, stalking.

following (noun)	trailing (noun)
the act of pursuing in an effort to overtake or capture	the pursuit (of a person or animal) by following tracks or marks they left behind
a group of followers or enthusiasts

following (adjective)	trailing (adjective)
going or proceeding or coming after in the same direction
in the desired direction
about to be mentioned or specified
immediately following in time or order