ballpoint pen vs Biro

ballpoint pen and Biro both are nouns.

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

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

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

Other synonyms of ballpoint pen include ballpen, ballpoint.

ballpoint pen (noun)	Biro (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