pet-food vs pet food

pet-food and pet food both are nouns.

Word	Noun	Adjective	Verb	Adverb
pet-food	Yes	No	No	No
pet food	Yes	No	No	No

As nouns, pet-food and pet food are synonyms defined as:

Other synonyms of pet-food include petfood.

pet-food (noun)	pet food (noun)
food prepared for animal pets	food prepared for animal pets