endoskeleton vs appendicular skeleton

endoskeleton and appendicular skeleton both are nouns.

Word	Noun	Adjective	Verb	Adverb
endoskeleton	Yes	No	No	No
appendicular skeleton	Yes	No	No	No

endoskeleton (noun)	appendicular skeleton (noun)
the internal skeleton; bony and cartilaginous structure (especially of vertebrates)	the part of the skeleton that includes the pectoral girdle and the pelvic girdle and the upper and lower limbs