The difference between Brainless and Dumb

When used as adjectives, brainless means having no brain, whereas dumb means unable to speak.

Dumb is also verb with the meaning: to silence.

check bellow for the other definitions of Brainless and Dumb

Brainless as an adjective (not comparable):

Having no brain.
Brainless as an adjective (comparable):

Unintelligent, with little common sense.

Dumb as an adjective (dated):

Unable to speak; lacking power of speech (kept in "deaf, dumb, and blind").

Examples:

"His younger brother was born dumb, and communicated with sign language."
Dumb as an adjective (dated):

Silent; unaccompanied by words.

Examples:

"dumb show"
Dumb as an adjective (informal, pejorative, especially of a person):

extremely stupid.

Examples:

"You are so dumb! You don't even know how to make toast!"
Dumb as an adjective (figuratively):

Pointless, foolish, lacking intellectual content or value.

Examples:

"This is dumb! We're driving in circles! We should have asked for directions an hour ago!"

"Brendan had the dumb job of moving boxes from one conveyor belt to another."
Dumb as an adjective:

Lacking brightness or clearness, as a colour.