Ugh - Microsoft is making a mess out of all these terms and confusing us all along the way. Based on a little help from this post, here's the lineup:

• Live Sync (formerly FolderShare). sync folders amongst machines. Currently PC only I think (FolderShare used to have Mac support). Used internally by Mesh to do sync
• Live Mesh - part of the Azure Services Platform. Contains the "Live Desktop" element along with machines (devices) and users to all sync amongst themselves.
• SkyDrive - just a hard drive in the sky (as of now, 25 GB storage, 50 MB per file). Web based access to items in various folders. Set access perms per folder.