There are: military engineers, civil engineers, structural engineers, geotechnical engineers, mechanical engineers, electrical engineers, industrial engineers, chemical engineers, aeronautical and aerospace engineers, and biomedical engineers - to name but a few. (And the 'Principal Engineer' grade exists in all of them - I've been everywhere man!)

What do they have in common? Applied physics.

How does your sort of "engineer" use applied physics?

(Or am I being narrow-minded?)