telemarketing vs selling

telemarketing and selling both are nouns.

Word	Noun	Adjective	Verb	Adverb
telemarketing	Yes	No	No	No
selling	Yes	No	No	No

As nouns, selling is a hypernym of telemarketing; that is, selling is a word with a broader meaning than telemarketing:

telemarketing: the use of the telephone as an interactive medium for promotion and sales
selling: the exchange of goods for an agreed sum of money

Other hypernyms of telemarketing include marketing, merchandising.

telemarketing (noun)	selling (noun)
the use of the telephone as an interactive medium for promotion and sales	the exchange of goods for an agreed sum of money