ballpen vs Biro

ballpen and Biro both are nouns.

Word	Noun	Adjective	Verb	Adverb
ballpen	Yes	No	No	No
Biro	Yes	No	No	No

As nouns, ballpen and Biro are synonyms defined as:

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

Other synonyms of ballpen include ballpoint, ballpoint pen.

ballpen (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