speed vs speed up

speed is a noun but speed up is not a noun.

Word	Noun	Adjective	Verb	Adverb
speed	Yes	No	Yes	No
speed up	No	No	Yes	No

As verbs, speed and speed up are synonyms defined as:

Other synonyms of speed include accelerate, quicken.

As verbs, speed and speed up are synonyms defined as:

Other synonyms of speed include accelerate.

speed (noun)	speed up (noun)
changing location rapidly
a central nervous system stimulant that increases energy and decreases appetite; used to treat narcolepsy and some forms of depression
a rate (usually rapid) at which something happens
the ratio of the focal length to the diameter of a (camera) lens system
distance travelled per unit time

speed (verb)	speed up (verb)
move faster	move faster
cause to move faster	cause to move faster
move very fast
travel at an excessive or illegal velocity
move hurridly