syllogism vs synthesis

syllogism and synthesis both are nouns.

Word	Noun	Adjective	Verb	Adverb
syllogism	Yes	No	No	No
synthesis	Yes	No	No	No

As nouns, synthesis is a hypernym of syllogism; that is, synthesis is a word with a broader meaning than syllogism:

syllogism: deductive reasoning in which a conclusion is derived from two premises
synthesis: reasoning from the general to the particular (or from cause to effect)

Other hypernyms of syllogism include deduction, deductive reasoning.

syllogism (noun)	synthesis (noun)
deductive reasoning in which a conclusion is derived from two premises	the combination of ideas into a complex whole
	reasoning from the general to the particular (or from cause to effect)
	the process of producing a chemical compound (usually by the union of simpler chemical compounds)