dichotomy vs categorisation

dichotomy and categorisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
dichotomy	Yes	No	No	No
categorisation	Yes	No	No	No

As nouns, categorisation is a hypernym of dichotomy; that is, categorisation is a word with a broader meaning than dichotomy:

dichotomy: being twofold; a classification into two opposed parts or subclasses
categorisation: a group of people or things arranged by class or category

Other hypernyms of dichotomy include categorization, classification.

dichotomy (noun)	categorisation (noun)
being twofold; a classification into two opposed parts or subclasses	the act of distributing things into classes or categories of the same type
	the basic cognitive process of arranging into classes or categories
	a group of people or things arranged by class or category