Actual breach occurs when there is no notice, like a person not turning up or delivering on the agreed day, as seen in Poussard v Spiers (opera singer failed to turn up)
Anticipatory breach is when one party informs in advance that they won't fulfill the contract, as in Hochester v De La Tour ('2 months in advance, don't need you anymore')
In case of an anticipatory breach, the innocent party must choose to wait and see if the breaching party fulfills the contract or decide to break the contract, but cannot do both; if they wait, they lose the right to claim
Warranty terms are less critical; breaching a warranty leads to compensation but not the end of the contract, as in Bettini v Gye where missing rehearsals led to a fine but not termination