TECHNICAL WRITTING??? waht is the difference between " process description" and "instructions"???

Answer 1

I suppose process description would be a description of the process, like
"The mash is heated, causing alcohol to evaporate more rapidly than water. The vapor is condensed, again with product condensing more rapidly"

Instructions might be what the operator does to make the process happen.
"Load the kettle with mash and start a fire. Heat to boiling and reduce to simmer. Adjust coolant flow in condeser to achieve a slow steady stream of clear volatile liquid." . . .

Answer 2

A process description is more of a "how and why". Instructions are more of a "how to".