sketch vs block out

sketch is a noun but block out is not a noun.

Word	Noun	Adjective	Verb	Adverb
sketch	Yes	No	Yes	No
block out	No	No	Yes	No

As verbs, block out is a hyponym of sketch; that is, block out is a word with a more specific, narrower meaning than sketch:

Other hyponyms of sketch include sketch out.

sketch (noun)	block out (noun)
preliminary drawing for later elaboration
short descriptive summary (of events)
a humorous or satirical drawing published in a newspaper or magazine
a brief literary description

sketch (verb)	block out (verb)
describe roughly or briefly or give the main points or summary of	plan where and when songs should be inserted into a theatrical production, or plan a theatrical production in general
make a sketch of	indicate roughly
	shield from light
	prevent from entering