hamburger vs beefburger

hamburger and beefburger both are nouns.

Word	Noun	Adjective	Verb	Adverb
hamburger	Yes	No	No	No
beefburger	Yes	No	No	No

As nouns, hamburger and beefburger are synonyms defined as:

hamburger and beefburger: a sandwich consisting of a fried cake of minced beef served on a bun, often with other ingredients

Other synonyms of hamburger include burger.

hamburger (noun)	beefburger (noun)
beef that has been ground	a sandwich consisting of a fried cake of minced beef served on a bun, often with other ingredients
a sandwich consisting of a fried cake of minced beef served on a bun, often with other ingredients