Missing gear vs secret sauce

I want to distinguish between the following two framings:

• missing gear/one wrong number problem/step function/understanding is discontinuous/payoff thresholds: "missing gear" doesn't imply that the last piece added is all that significant -- it just says that adding it caused a huge jump in capabilities.
• secret sauce for intelligence/small number of breakthroughs: "small number of breakthroughs" says that the last added piece must have been a significant piece (which is what a breakthrough is).

I'm not sure how different these two actually are. But when thinking about discontinuities, I've noticed that I am somewhat inconsistent about conflating these two and distinctly visualizing them.

Term	Definition
Missing gear
Secret sauce
One wrong number function
Step function
Understanding is discontinuous
Payoff thresholds
One algorithm
Lumpy AI progress
Intelligibility of intelligence
Simple core algorithm
Small number of breakthroughs needed for AGI