Term Kind Topic What it is
Feature Parity Trap concept Rebuild vs Re-architect The expectation that a replacement system must match every behaviour of the old one before it can be adopted, which is what makes rewrites never finish.
Greenfield Velocity Illusion Rewrite Head Start, Front-Loaded Rewrite Progress concept Rebuild vs Re-architect The early speed advantage a from-scratch rebuild shows because it is running with all the real constraints switched off, which makes its estimate systematically wrong in the same direction every time.