I started using the term diff debt a couple of weeks ago, and the first reaction I got was pretty consistent: "isn't that just technical debt?"
It isn't. And honestly, the gap between the two is the entire reason I needed a new word for it.
Technical debt, the version we already know
Ward Cunningham gave us the technical debt metaphor back in the early 90s, and it stuck because it's accurate. You ship something quick and messy to hit a deadline, and you pay interest on it later, every time you have to work around the shortcut you took.
The part that never gets said out loud is that technical debt assumes you understood what you shipped. You picked the hacky solution over the clean one on purpose. You could open that file right now and explain, line by line, why it's ugly and what the "right" version would look like.
