SUS- and SRM- Portal

Hallo All,

There are two system SUS and SRM, which are on the same server, but have different client (XXX and YYY).

Please tell me, as suppliers and buyers should go to a web application?

portal where suppliers are working to process their data (addresses, contracts, etc.) are the same as where they work and purchaser? that is a common portal(a reference to Logon suppliers and buyers), but depending on the user's role (supplier / buyer), they see different screens. So this or not?

or is there a separate portal for suppliers and a separate portal for purchaser, 2 links to login?

Thank You