holding pen vs holding yard

holding pen and holding yard both are nouns.

Word	Noun	Adjective	Verb	Adverb
holding pen	Yes	No	No	No
holding yard	Yes	No	No	No

As nouns, holding pen and holding yard are synonyms defined as:

holding pen and holding yard: a pen where livestock is temporarily confined

Other synonyms of holding pen include holding paddock.

holding pen (noun)	holding yard (noun)
a pen where livestock is temporarily confined	a pen where livestock is temporarily confined