clog vs silt up

clog is a noun but silt up is not a noun.

Word	Noun	Adjective	Verb	Adverb
clog	Yes	No	Yes	No
silt up	No	No	Yes	No

As verbs, silt up is a hyponym of clog; that is, silt up is a word with a more specific, narrower meaning than clog:

Other hyponyms of clog include gum up, block, choke up, lug, stuff, silt.

clog (noun)	silt up (noun)
a dance performed while wearing shoes with wooden soles; has heavy stamping steps
any object that acts as a hindrance or obstruction
footwear usually with wooden soles

clog (verb)	silt up (verb)
impede with a clog or as if with a clog	become chocked with silt
fill to excess so that function is impaired
coalesce or unite in a mass
become or cause to become obstructed
impede the motion of, as with a chain or a burden
dance a clog dance