beat vs rhythm

beat and rhythm both are nouns.

Word	Noun	Adjective	Verb	Adverb
beat	Yes	Yes	Yes	No
rhythm	Yes	No	No	No

As nouns, beat and rhythm are synonyms defined as:

Other synonyms of beat include musical rhythm.

beat (noun)	rhythm (noun)
the act of beating to windward; sailing as close as possible to the direction from which the wind is blowing	natural family planning in which ovulation is assumed to occur 14 days before the onset of a period (the fertile period would be assumed to extend from day 10 through day 18 of her cycle)
a stroke or blow	recurring at regular intervals
a regular rate of repetition	(architecture) the repetitive use of a group of visual elements to establish a recognizable pattern
the basic rhythmic unit in a piece of music	the arrangement of spoken words alternating stressed and unstressed elements
(prosody) the accent in a metrical foot of verse	the basic rhythmic unit in a piece of music
the rhythmic contraction and expansion of the arteries with each beat of the heart	an interval during which a recurring sequence of events occurs
the sound of stroke or blow
a regular route for a sentry or policeman
a member of the beat generation; a nonconformist in dress and behavior
a single pulsation of an oscillation produced by adding two waves of different frequencies; has a frequency equal to the difference between the two oscillations

beat (adjective)	rhythm (adjective)
very tired

beat (verb)	rhythm (verb)
wear out completely
be a mystery or bewildering to
come out better in a competition, race, or conflict
beat through cleverness and wit
hit repeatedly
give a beating to; subject to a beating, either as a punishment or as an act of aggression
stir vigorously
strike (a part of one's own body) repeatedly, as in great emotion or in accompaniment to music
strike (water or bushes) repeatedly to rouse animals for hunting
shape by beating
make by pounding or trampling
produce a rhythm by striking repeatedly
move rhythmically
sail with much tacking or with difficulty
move with a flapping motion
indicate by beating, as with the fingers or drumsticks
move with a thrashing motion
move with or as if with a regular alternating motion
make a rhythmic sound
make a sound like a clock or a timer
glare or strike with great intensity
avoid paying
be superior