Thoughts and Urges

How do I tell the difference between a thought or want and urge. I’ve started doing the urge jar but question when I am having a urge.

For example, I was at the baker’s getting rolls for lunch and thought about buying a bun to eat straight away. I immediately then thought, “that’s what the old me used to do” and no longer wanted the bun. Is this resisting an urge and warrants a pebble in my jar or is this modified thoughts and reward on its own?