want to learn details
A very important difference. A purchase req is sent to one company and is the official order another company issues to buy something. An RFQ (Request For Quote) is sent to several companies and is an invitation for all vendors to give their best price on selling something but does NOT indicate a contract to buy. If your RFQ is the best of all the RFQs the buyer receives, the vendor will get the Purchase Requisition.
Both purchase requisition and RFQ give the information which the buyer request the supplier to provide.
I think we can take both as the buyer's requirement.