small vs modest

small is a noun but modest is not a noun.

Word	Noun	Adjective	Verb	Adverb
small	Yes	Yes	No	Yes
modest	No	Yes	No	No

As adjectives, small and modest are synonyms defined as:

Other synonyms of small include humble, low, lowly.

As adjectives, small and modest are synonyms defined as:

Other synonyms of small include minor, pocket-size, pocket-sized, small-scale.

As adjectives, small and modest are synonyms defined as:

small (noun)	modest (noun)
a garment size for a small person
the slender part of the back

small (adjective)	modest (adjective)
limited or below average in number or quantity or magnitude or extent	not offensive to sexual mores in conduct or appearance
made to seem smaller or less (especially in worth)	marked by simplicity; having a humble opinion of yourself
have fine or very small constituent particles	humble in spirit or manner; suggesting retiring mildness or even cowed submissiveness
low or inferior in station or quality	low or inferior in station or quality
relatively moderate, limited, or small	relatively moderate, limited, or small
slight or limited; especially in degree or intensity or scope	not large but sufficient in size or amount
lowercase	free from pomp or affectation
not large but sufficient in size or amount
(of a voice) faint
(of children and animals) young, immature

small (adverb)	modest (adverb)
on a small scale