tremor vs shudder

tremor and shudder both are nouns.

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

As nouns, tremor and shudder are synonyms defined as:

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

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

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