astrologist vs prognosticator

astrologist and prognosticator both are nouns.

Word	Noun	Adjective	Verb	Adverb
astrologist	Yes	No	No	No
prognosticator	Yes	No	No	No

As nouns, prognosticator is a hypernym of astrologist; that is, prognosticator is a word with a broader meaning than astrologist:

astrologist: someone who predicts the future by the positions of the planets and sun and Moon
prognosticator: someone who makes predictions of the future (usually on the basis of special knowledge)

Other hypernyms of astrologist include forecaster, predictor, soothsayer.

astrologist (noun)	prognosticator (noun)
someone who predicts the future by the positions of the planets and sun and Moon	someone who makes predictions of the future (usually on the basis of special knowledge)