pet sitter vs critter sitter

pet sitter and critter sitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
pet sitter	Yes	No	No	No
critter sitter	Yes	No	No	No

As nouns, pet sitter and critter sitter are synonyms defined as:

pet sitter and critter sitter: someone left in charge of pets while their owners are away from home

pet sitter (noun)	critter sitter (noun)
someone left in charge of pets while their owners are away from home	someone left in charge of pets while their owners are away from home