royal vs regal

royal is a noun but regal is not a noun.

Word	Noun	Adjective	Verb	Adverb
royal	Yes	Yes	No	No
regal	No	Yes	No	No

As adjectives, royal and regal are synonyms defined as:

Other synonyms of royal include imperial, majestic, purple.

royal (noun)	regal (noun)
stag with antlers of 12 or more branches
a sail set next above the topgallant on a royal mast

royal (adjective)	regal (adjective)
of or relating to or indicative of or issued or performed by a king or queen or other monarch	belonging to or befitting a supreme ruler
established or chartered or authorized by royalty
invested with royal power as symbolized by a crown
being of the rank of a monarch
belonging to or befitting a supreme ruler