Distinguish two things I keep confusing

Two terms you nod along to but could not reliably tell apart.

I keep confusing the two things below. Separate them for good.

1. **One-line definition of each**, written so the definitions cannot be swapped without becoming wrong.
2. **Why they get confused.** What they genuinely share.
3. **The decisive difference.** The single test I can apply to tell which one I am looking at.
4. **Side-by-side table** on the dimensions that actually differ. Skip dimensions where they are the same.
5. **Three examples**, one clearly A, one clearly B, one borderline. Explain the borderline case properly.
6. **The cost of mixing them up**: what goes wrong in practice.

A:
B:

Scrutinising ideas. Where a concept stops working, what people get wrong, and whether a claim holds up.