illation vs abstract thought

illation and abstract thought both are nouns.

Word	Noun	Adjective	Verb	Adverb
illation	Yes	No	No	No
abstract thought	Yes	No	No	No

As nouns, abstract thought is a hypernym of illation; that is, abstract thought is a word with a broader meaning than illation:

illation: the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation
abstract thought: thinking that is coherent and logical

Other hypernyms of illation include logical thinking, reasoning.

illation (noun)	abstract thought (noun)
the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation	thinking that is coherent and logical