think vs focus

think and focus both are nouns.

Word	Noun	Adjective	Verb	Adverb
think	Yes	No	Yes	No
focus	Yes	No	Yes	No

As verbs, focus is a hyponym of think; that is, focus is a word with a more specific, narrower meaning than think:

think: use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments
focus: direct one's attention on something

As verbs, focus is a hypernym of think; that is, focus is a word with a broader meaning than think:

Other hypernyms of think include center, centre, concentrate, pore, rivet.

think (noun)	focus (noun)
an instance of deliberate thinking	maximum clarity or distinctness of an image rendered by an optical system
	maximum clarity or distinctness of an idea
	the concentration of attention or energy on something
	a fixed reference point on the concave side of a conic section
	a point of convergence of light (or other radiation) or a point from which it diverges
	a central point or locus of an infection in an organism
	special emphasis attached to something

think (verb)	focus (verb)
bring into a given condition by mental preoccupation	become focussed or come into focus
use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments	put (an image) into focus
judge or regard; look upon; judge	direct one's attention on something
recall knowledge from memory; have a recollection	bring into focus or alignment; to converge or cause to converge; of ideas or emotions
expect, believe, or suppose	cause to converge on or toward a central point
have in mind as a purpose
be capable of conscious thought
focus one's attention on a certain state
decide by pondering, reasoning, or reflecting
ponder; reflect on, or reason about
have or formulate in the mind
dispose the mind in a certain way
imagine or visualize