Scenario for diff. Pricing Proc. at Quotation and Sales Order

Hi Experts -

I know the we can have different Pricing Proc assigned to both Quotation level and Sales Order level but someone pls give me example of a business scenario where pricing at sales order level can be different than quotation? Why would we do it and what functionality in SAP would it drive.

(Sure we cannot offer discounts at quotation level, it can just be displayed) Any thoughts

Thanks,

MS