garbage collection vs pickup

garbage collection and pickup both are nouns.

Word	Noun	Adjective	Verb	Adverb
garbage collection	Yes	No	No	No
pickup	Yes	No	No	No

As nouns, pickup is a hypernym of garbage collection; that is, pickup is a word with a broader meaning than garbage collection:

garbage collection (noun)	pickup (noun)
the collection and removal of garbage	the act or process of picking up or collecting from various places
	the act of taking aboard passengers or freight
	a light truck with an open body and low sides and a tailboard
	an electro-acoustic transducer that is the part of the arm of a record player that holds the needle and that is removable
	mechanical device consisting of a light balanced arm that carries the cartridge
	anything with restorative powers
	the attribute of being capable of rapid acceleration
	a warrant to take someone into custody
	a casual acquaintance; often made in hope of sexual relationships