archaeobacteria vs archaebacterium

archaeobacteria and archaebacterium both are nouns.

Word	Noun	Adjective	Verb	Adverb
archaeobacteria	Yes	No	No	No
archaebacterium	Yes	No	No	No

As nouns, archaeobacteria and archaebacterium are synonyms defined as:

archaeobacteria and archaebacterium: considered ancient life forms that evolved separately from bacteria and blue-green algae

Other synonyms of archaeobacteria include archaebacteria, archeobacteria.

archaeobacteria (noun)	archaebacterium (noun)
considered ancient life forms that evolved separately from bacteria and blue-green algae	considered ancient life forms that evolved separately from bacteria and blue-green algae