Is provisional receipt equals official receipt?

Answer 1

No it is not.

1.) A Provisional receipt by definition is subject to certain provisions as may be laid out by the issuer of the receipt.

2.) in general business practice a provisional receipt is usually issued as an acknowledgement of receipt of money or material by someone who is either not authorised to issue a final confirmed official receipt or could not carry out sufficient due diligence in receiving the money/goods and hence issues a provisional receipt till such time as a final confirmed receipt is issued.

While for most practical purposes a provisional receipt may suffice, it is always prudent to ensure the final confirmed receipt as early as possible.