hooker vs harlot

hooker and harlot both are nouns.

Word	Noun	Adjective	Verb	Adverb
hooker	Yes	No	No	No
harlot	Yes	No	No	No

As nouns, harlot is a hypernym of hooker; that is, harlot is a word with a broader meaning than hooker:

hooker (noun)	harlot (noun)
a prostitute who attracts customers by walking the streets	a woman who engages in sexual intercourse for money
(rugby) the player in the middle of the front row of the scrum who tries to capture the ball with the foot
a golfer whose shots typically curve left (for right-handed golfers)