treatise vs tract

treatise and tract both are nouns.

Word	Noun	Adjective	Verb	Adverb
treatise	Yes	No	No	No
tract	Yes	No	No	No

As nouns, tract is a hyponym of treatise; that is, tract is a word with a more specific, narrower meaning than treatise:

treatise: a formal exposition
tract: a brief treatise on a subject of interest; published in the form of a booklet

Other hyponyms of treatise include dissertation, thesis, pamphlet, monograph.

treatise (noun)	tract (noun)
a formal exposition	a bundle of myelinated nerve fibers following a path through the brain
	a system of body parts that together serve some particular purpose
	a brief treatise on a subject of interest; published in the form of a booklet
	an extended area of land