propagation vs redshift

propagation and redshift both are nouns.

Word	Noun	Adjective	Verb	Adverb
propagation	Yes	No	No	No
redshift	Yes	No	No	No

As nouns, redshift is a hyponym of propagation; that is, redshift is a word with a more specific, narrower meaning than propagation:

propagation: the movement of a wave through a medium
redshift: (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding

Other hyponyms of propagation include Doppler effect, Doppler shift, red shift, wave front.

propagation (noun)	redshift (noun)
the act of producing offspring or multiplying by such production	(astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding
the spreading of something (a belief or practice) into new regions
the movement of a wave through a medium