shock absorber vs muffler

shock absorber and muffler both are nouns.

Word	Noun	Adjective	Verb	Adverb
shock absorber	Yes	No	No	No
muffler	Yes	No	No	No

As nouns, muffler is a hypernym of shock absorber; that is, muffler is a word with a broader meaning than shock absorber:

shock absorber: a mechanical damper; absorbs energy of sudden impulses
muffler: a device that decreases the amplitude of electronic, mechanical, acoustical, or aerodynamic oscillations

Other hypernyms of shock absorber include damper.

shock absorber (noun)	muffler (noun)
a mechanical damper; absorbs energy of sudden impulses	a scarf worn around the neck
	a tubular acoustic device inserted in the exhaust system that is designed to reduce noise
	a device that decreases the amplitude of electronic, mechanical, acoustical, or aerodynamic oscillations