catching pen vs catch pen

catching pen and catch pen both are nouns.

Word	Noun	Adjective	Verb	Adverb
catching pen	Yes	No	No	No
catch pen	Yes	No	No	No

As nouns, catching pen and catch pen are synonyms defined as:

catching pen and catch pen: a small or medium containment area for holding animals.

catching pen (noun)	catch pen (noun)
a small or medium containment area for holding animals.	a small or medium containment area for holding animals.