How does a computer distinguish between Data and Instructions?

Question

I watched a video on an 8-bit pc being fed a program - manually, using physics switches.

The fed program was:

MAIN:
    0000 0001 0100     # 0 = LDA          


        

Answer 1

In computer systems an instruction's address comes from PC (Program Counter) and data's address don't come from PC. This is how they are differentiated.