In my past efforts in purchasing crate engines, I've had a sometimes tough time trying to reconcile the differences, and there always are, of one builder's crate engine from another builder's crate engine. Do they both have forged steel cranks, I-beam versus H-beam connecting rods, CNC'ed aluminum heads versus non-CNC'ed aluminum heads, SB's have a variety of choices too,
oil pans, carbs, camshafts and their specs, old seasoned versus new engine blocks (Dart, World, Keith Black, etc.)? Along with what Jay mentions above.
While the engine builders can make these comparisons for the consumer, I think the ultimate responsibility for making an informed choice is us the consumer, which includes companies like Jay's that sell complete packages.