lapdog vs Canis familiaris

lapdog and Canis familiaris both are nouns.

Word	Noun	Adjective	Verb	Adverb
lapdog	Yes	No	No	No
Canis familiaris	Yes	No	No	No

As nouns, Canis familiaris is a hypernym of lapdog; that is, Canis familiaris is a word with a broader meaning than lapdog:

lapdog: a dog small and tame enough to be held in the lap
Canis familiaris: a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds

Other hypernyms of lapdog include dog, domestic dog.

lapdog (noun)	Canis familiaris (noun)
a dog small and tame enough to be held in the lap	a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds