Biro vs ballpoint pen

Biro and ballpoint pen both are nouns.

Word	Noun	Adjective	Verb	Adverb
Biro	Yes	No	No	No
ballpoint pen	Yes	No	No	No

As nouns, Biro and ballpoint pen are synonyms defined as:

Biro and ballpoint pen: a pen that has a small metal ball as the point of transfer of ink to paper

Other synonyms of Biro include ballpen, ballpoint.

Biro (noun)	ballpoint pen (noun)
a pen that has a small metal ball as the point of transfer of ink to paper	a pen that has a small metal ball as the point of transfer of ink to paper