Similar but not the same.

Esta sección tendrá como objetivo aclarar dudas de palabras que facilmente se confunden o son parecidas y no se sabe bien cuando se usa una u otra.


Quick/ Fast:

Los dos son adjetivos que significan rápido.
¿Cuando se usa uno y cuando otro?

-Quick is used with events of short or negligible (insignificante, desdeñable) duration.

-Fast is used for events of longer duration or clearly measurable (medibles).

-Defination of quick: Done, proceeding or oCCurring with promptness or rapidity.
It´s an action, a process that is completed in a short period of time.

-Defination of fast: moving or able to move or take effect quickly.
An action that oCCurs in a short period of time.


i.e:

-A quick car is a car that have a fast response (from 0 till 100 kms in 3 seconds).

-A fast car is a car that can do 250 kms per hour.


To be honest, the difference between "fast" and "quick" (when used as adjectives) isn't articulated in any solid rules, it depends on usage.
These two words are synonyms and they can't arbitrarily replace each other. Looking at what is being described and whether or not it is in a "fixed" (quick) or "animated" (fast) state may be the best way to handle this particular facet of the English language.


Speaking of cars...