kitchen garden vs vegetable patch

kitchen garden and vegetable patch both are nouns.

Word	Noun	Adjective	Verb	Adverb
kitchen garden	Yes	No	No	No
vegetable patch	Yes	No	No	No

As nouns, kitchen garden and vegetable patch are synonyms defined as:

kitchen garden and vegetable patch: a small garden where vegetables are grown

Other synonyms of kitchen garden include vegetable garden.

kitchen garden (noun)	vegetable patch (noun)
a small garden where vegetables are grown	a small garden where vegetables are grown