Siamese cat vs domestic cat

Siamese cat and domestic cat both are nouns.

Word	Noun	Adjective	Verb	Adverb
Siamese cat	Yes	No	No	No
domestic cat	Yes	No	No	No

As nouns, domestic cat is a hypernym of Siamese cat; that is, domestic cat is a word with a broader meaning than Siamese cat:

Siamese cat: a slender short-haired blue-eyed breed of cat having a pale coat with dark ears paws face and tail tip
domestic cat: any domesticated member of the genus Felis

Other hypernyms of Siamese cat include Felis catus, Felis domesticus, house cat.

Siamese cat (noun)	domestic cat (noun)
a slender short-haired blue-eyed breed of cat having a pale coat with dark ears paws face and tail tip	any domesticated member of the genus Felis