royal tennis vs court tennis

royal tennis and court tennis both are nouns.

Word	Noun	Adjective	Verb	Adverb
royal tennis	Yes	No	No	No
court tennis	Yes	No	No	No

As nouns, royal tennis and court tennis are synonyms defined as:

royal tennis and court tennis: an ancient form of tennis played in a four-walled court

Other synonyms of royal tennis include real tennis.

royal tennis (noun)	court tennis (noun)
an ancient form of tennis played in a four-walled court	an ancient form of tennis played in a four-walled court