undertake vs take on

undertake and take on both are verbs.

Word	Noun	Adjective	Verb	Adverb
undertake	No	No	Yes	No
take on	No	No	Yes	No

As verbs, undertake and take on are synonyms defined as:

Other synonyms of undertake include tackle.

undertake (verb)	take on (verb)
promise to do or accomplish	take on a certain form, attribute, or aspect
enter into a contractual arrangement	contend against an opponent in a sport, game, or battle
enter upon an activity or enterprise	admit into a group or community
accept as a charge	accept as a challenge
accept as a challenge	take on titles, offices, duties, responsibilities