Here’s a explanation of the difference:
- Transition state:
- Very unstable and exists for a tiny fraction of a second.
- Occurs at the highest energy point when reactants are changing into products.
- Cannot be isolated.
- Intermediate:
- More stable than the transition state and lasts longer.
- Forms between steps in a reaction.
- Can sometimes be detected or isolated.
In short:
- Transition state = momentary high-energy peak.
- Intermediate = short-lived species between steps.