Difference between an irrevocable offer and an offer that lapses

Offers to purchase usually contain one of the following clauses:
This offer is irrevocable until 1 February 2024 (date as stipulated by purchaser) OR
This offer lapses on 1 February 2024.
The wording used has different effects on the lapsing of the offer. An irrevocable offer is open for acceptance by the seller and cannot be withdrawn by the purchaser before the lapsing of the stipulated period. The irrevocable nature of the offer simply falls away after the specified date and it becomes revocable, should the purchaser choose to withdraw. Until the offer is revoked, it remains open and is capable of acceptance by the seller.
Should the offer to purchase read that the offer lapses on 1 February 2024 the seller must accept it before midnight on the 1st of February 2024. Thereafter the offer lapses and will be of no force and effect on the morning of 2 February.
The advantage of the irrevocable offer clause is that it provides flexibility where the seller may not be able to sign the offer on a specific date and the purchaser is willing to not revoke the offer after the specified date.