shudder vs tremor

shudder and tremor both are nouns.

Word	Noun	Adjective	Verb	Adverb
shudder	Yes	No	Yes	No
tremor	Yes	No	Yes	No

As nouns, shudder and tremor are synonyms defined as:

shudder and tremor: an involuntary vibration (as if from illness or fear)

shudder (noun)	tremor (noun)
an involuntary vibration (as if from illness or fear)	an involuntary vibration (as if from illness or fear)
an almost pleasurable sensation of fright	a small earthquake
	shaking or trembling (usually resulting from weakness or stress or disease)

shudder (verb)	tremor (verb)
shake, as from cold	shake with seismic vibrations
tremble convulsively, as from fear or excitement