In what way? I'm genuinely curious; I would describe an engineer who is provided to build a customer product alongside a customer as either a "contractor" or a "consultant," depending mostly on their employer. A security clearance just changes what customers and products they work for.

Contractor makes sense, consultant is a bit weird because the typical understanding is that a consultant comes in to share knowledge, not build product.

Then you're not familiar with software consultancy because that's exactly what they do.

Ah ok then let’s just call them contractors because that’s what exactly what they do.

Ok they are "consultants" with a federally guaranteed moat.