What are the differences between proforma invoice and commercial invoice?

Proforma invoice is a written proposal, issued by the exporter, which contains the terms and conditions of the foreign trade transaction. 

Proforma invoice is issued at the beginning of the transaction and it would not be accepted as a final document. 

It can be amended even after it is signed by both parties.

Commercial invoice also states the details of the transaction with one exception. 

Commercial invoice issued in order to complete the export and import operation in a foreign trade transaction, as a result its contents are final and are not subject to any further change or amendment.

PS: All corrections made on the face of the commercial invoice have to be authenticated by the issuer.

Today I would like to mention the differences between a proforma invoice and a commercial invoice.