To convince is to change what someone believes. To persuade is to move them to do something. You can convince someone that a plan is sound without persuading them to fund it. Traditionally, convince takes "that" or "of", while persuade takes "to".
The core difference
Belief versus action, with a grammatical tell.
- convince — change a belief: convince her that it works, convinced of his innocence.
- persuade — prompt an action: persuade him to sign.
The construction rule
Traditionally convince takes that or of, never an infinitive. So "convince him to leave" was objected to, with "persuade him to leave" the correct form. That objection has weakened considerably and "convince to" is now common, but the underlying distinction — belief versus action — remains useful.
Why it is worth keeping
Because the two can come apart in ways that matter. A jury may be convinced of a fact and still not be persuaded to convict. Collapsing the words loses the ability to say that.
Frequently asked questions
Is "convince him to" wrong?
It was traditionally objected to — persuade takes the infinitive, convince takes that or of. The objection has weakened and the construction is now common.
What is the underlying difference?
Convince changes a belief; persuade prompts an action.
Can you convince someone without persuading them?
Yes — they may accept your reasoning and still decline to act on it.