No. Mil-spec is an actual certified standard

Military grade is basically just “we made this shit to look like it’d be good as a prop in a movie” no actual standards, just good enough to sorta kinda sometimes work and is made as cheap as possible.

Edit; interesting comment by the other fella in the same reply chain, maybe “military grade” also encompasses stuff that’s made for specific purposes but doesn’t need to withstand rigorous standards, just be good enough for this one thing this one time and not much else

Granted, YMMV depending on country and region.

Yup.

EDIT: I see someone else commented that they're not the same. The truth is... it depends.

When I was serving in the military, we used the two terms interchangeably. They were basically the same thing to us. Although "military grade" is a more common term in the civilian sector, we would still use it when working with contractors on custom military equipment.

So if you want to be pendantic, mil-spec may be the more official term in the military. But in practice, we don't really differentiate between the two terms.