Intents and user operations in account abstraction sound similar - they both are txs executed on a users behalf by a single message. But there is one key difference. 

User operations = action 

Intents = outcome

Composable Intent-Centric protocol for Web3 app

Intent example could be: 

Buy grapes when they hit x price. If the price climbs by 10 cents, swap them for apples.

If they fall 10 cents, swap for pears. 

This is the outcome I want done, and I don’t care which marketplace you use to fill my order. If you accomplish it, I’ll give you a few grapes in return.