task vs undertaking

task and undertaking both are nouns.

Word	Noun	Adjective	Verb	Adverb
task	Yes	No	Yes	No
undertaking	Yes	No	No	No

As nouns, task and undertaking are synonyms defined as:

Other synonyms of task include labor, labour, project.

task (noun)	undertaking (noun)
a specific piece of work required to be done as a duty or for a specific fee	any piece of work that is undertaken or attempted
any piece of work that is undertaken or attempted	the trade of a funeral director

task (verb)	undertaking (verb)
use to the limit
assign a task to