speak vs talk down

speak and talk down both are verbs.

Word	Noun	Adjective	Verb	Adverb
speak	No	No	Yes	No
talk down	No	No	Yes	No

As verbs, talk down is a hyponym of speak; that is, talk down is a word with a more specific, narrower meaning than speak:

speak (verb)	talk down (verb)
express in speech	belittle through talk
exchange thoughts; talk with	speak in a condescending manner, as if to a child
use language	direct and control (the flight of an airplane during landing) via radio
give a speech to
make a characteristic or natural sound