battleground vs field of battle

battleground and field of battle both are nouns.

Word	Noun	Adjective	Verb	Adverb
battleground	Yes	No	No	No
field of battle	Yes	No	No	No

As nouns, battleground and field of battle are synonyms defined as:

battleground and field of battle: a region where a battle is being (or has been) fought

Other synonyms of battleground include battlefield, field, field of honor.

battleground (noun)	field of battle (noun)
a region where a battle is being (or has been) fought	a region where a battle is being (or has been) fought