earth tremor vs temblor

earth tremor and temblor both are nouns.

Word	Noun	Adjective	Verb	Adverb
earth tremor	Yes	No	No	No
temblor	Yes	No	No	No

As nouns, temblor is a hypernym of earth tremor; that is, temblor is a word with a broader meaning than earth tremor:

earth tremor: a small earthquake
temblor: shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity

Other hypernyms of earth tremor include earthquake, quake, seism.

earth tremor (noun)	temblor (noun)
a small earthquake	shaking and vibration at the surface of the earth resulting from underground movement along a fault plane or from volcanic activity