Not sure if it applies to engineers, but there's a difference in the job description between defining and implementing. Sometimes someone knows some theory, does some math and is done. And his or her result is passed to another person that implements it. Sometimes it's the same person doing both, but probably less often. Sometimes the implementer grows and starts putting down some ground rules (becomes an architect) or the other way round (for example there because might be more jobs for implementers).

Perhaps another distinction is between trying something and see if it works, and knowing it will work (or won't work) before it's implemented. Then the difference is between knowing from experience and knowing from having studied the theory (and having worked through the proofs).