Confusion on understanding pipes and streams?

I read about pipes and streams and I’m still confused on how it’s implemented.

A program is started and it reads data from “standard input” stream (stdin), which is where the keyboard sends data to.

My question is, how is that different from a pipe? Piping allows me to have a process that sends data to a pipe, and another process is reading data from it.

When the keyboard is pressed, data is sent to stdin and a program is reading data from this same stream.

A "read" operation is executed as soon as data is sent to this stream.