theta rhythm vs theta wave

theta rhythm and theta wave both are nouns.

Word	Noun	Adjective	Verb	Adverb
theta rhythm	Yes	No	No	No
theta wave	Yes	No	No	No

As nouns, theta rhythm and theta wave are synonyms defined as:

theta rhythm and theta wave: the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude

theta rhythm (noun)	theta wave (noun)
the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude	the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude