racker vs attender

racker and attender both are nouns.

Word	Noun	Adjective	Verb	Adverb
racker	Yes	No	No	No
attender	Yes	No	No	No

As nouns, attender is a hypernym of racker; that is, attender is a word with a broader meaning than racker:

racker: an attendant who puts pool or billiard balls into a rack
attender: someone who waits on or tends to or attends to the needs of another

Other hypernyms of racker include attendant, tender.

racker (noun)	attender (noun)
an attendant who puts pool or billiard balls into a rack	someone who waits on or tends to or attends to the needs of another
	a person who is present and participates in a meeting
	someone who listens attentively