WSS = SharePoint Foundation (simpler new name for “WSS”)MOSS = SharePoint Server (simpler name for “MOSS”)
In terms of product features SharePoint Server continues to have Standard and Enterprise CAL tiers of features.
Microsoft also enhancing free basic search offering in Search Server Express 2010. The FAST Search capabilities will be available via the FAST Search for SharePoint add-on server for customers with the Enterprise CAL.
SharePoint Designer remain is free.
SharePoint Workspace (formerly Groove) is included in Office Professional Plus.