An invoice from a vendor is the bill that is received by the purchaser of goods or services from an outside supplier. The vendor invoice lists the quantities of items, brief descriptions, prices, total amount due, credit terms, where to remit payment, etc.
A voucher is an internal document used in a company's accounts payable department in order to collect and organize the necessary documentation and approvals before paying a vendor invoice. The voucher acts as a cover page to which the following will be attached: vendor invoice, company's purchase order, company's receiving report, and other information needed to process the vendor invoice for payment.
