Supplier management is your inside view of the companies you buy from. This is theirs: suppliers keep their details current, bid for work, submit sealed quotes, acknowledge orders and invoice, all in one place. No licence. No email to chase.
A supplier signs in and sees their whole side of it: opportunities to bid for, orders to fulfil, contracts to sign, documents to keep current, invoices raised. It replaces the email thread that usually carries all of this, and costs them nothing.
Two ways in, on one screen. The buyer invites a supplier into a private RFQ, or the supplier finds a public tender. Follow the categories you supply and a match notifies you as it opens.