focus vs immerse

focus is a noun but immerse is not a noun.

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

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

Other hyponyms of focus include absorb, engross, engulf, plunge, soak up, steep, recall, think, zoom in, hear, listen, take heed.

focus (noun)	immerse (noun)
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

focus (verb)	immerse (verb)
become focussed or come into focus	devote (oneself) fully to
put (an image) into focus	cause to be immersed
direct one's attention on something	thrust or throw into
bring into focus or alignment; to converge or cause to converge; of ideas or emotions	enclose or envelop completely, as if by swallowing
cause to converge on or toward a central point