Buzzer vs Bzzt - What's the difference?

As a noun buzzer

is one who, or that which, buzzes; an insect that buzzes.

the sound of a buzzer or of electricity.

(wikipedia buzzer)

(en noun)

One who, or that which, buzzes; an insect that buzzes.

* Shakespeare

And wants not buzzers to infect his ear / With pestilent speeches of his father's death.

A device that makes a buzzing sound.

:* If you think you know the answer to the question, hit the buzzer as fast as you can.

A police badge.

* 1939 , (Raymond Chandler), The Big Sleep , Penguin 2011, p. 28:

I flipped my wallet open on her desk and let her look at the buzzer pinned to the flap.

(en interjection)

(onomatopoeia) The sound of a buzzer or of electricity.

* 1921 , Alfred Emanuel Smith, New Outlook

The buzzer on Matthew's desk rang violently at this point, bzzt -bzzt...

* 2000 , Linda P Acredolo, Susan Goodwyn, Baby minds: brain-building games your baby will love

You sing him a new song, bzzt' — a connection is made. You tickle his toes, ' bzzt — there goes another.

* 2001 , Keith R A DeCandido, Rockne S O'Bannon, Farscape: House of Cards

Pressing an imaginary button, Crichton said, "Bzzt ! Wrong answer."