They look similar and point in opposite directions. Breadcrumbing dangles just enough to keep you interested — the goal is to keep you. Curving is trying to get rid of you without having to say the word 'no'.
Side by side
Aspect
Curving
Breadcrumbing
The goal
To lose you gently
To keep you around
Warmth
Politely flat
Deliberately warm
Plans
Always deflected
Dangled, then dropped
If you left
Relief
They'd re-engage
What each one means
Curving
Curving is turning down someone's romantic advances — in dating slang usually the soft version, rejecting someone without ever saying no — staying in contact and replying just enough, while deflecting every attempt to make a plan or define the relationship.
Breadcrumbing is when someone gives you just enough attention — a like, a flirty text, a “miss you” — to keep you interested, without ever intending to commit or meet. A trail of crumbs that leads nowhere.