wave shape vs undulation

wave shape and undulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
wave shape	Yes	No	No	No
undulation	Yes	No	No	No

As nouns, undulation is a hypernym of wave shape; that is, undulation is a word with a broader meaning than wave shape:

wave shape: the shape of a wave illustrated graphically by plotting the values of the period quantity against time
undulation: (physics) a movement up and down or back and forth

Other hypernyms of wave shape include wave.

wave shape (noun)	undulation (noun)
the shape of a wave illustrated graphically by plotting the values of the period quantity against time	(physics) a movement up and down or back and forth
	wavelike motion; a gentle rising and falling in the manner of waves
	an undulating curve