CtR is this containerized install-from-web platform that Microsoft came up with for .NET applications. Yeah, it's actually a lot of years old. But generally speaking, if you get an Office disc or ISO file (say, from Microsoft's Volume Licensing Center), and install it, you get a traditional Office install that gets serviced via KB downloads from Windows Update. If you get Office via a web download from office.com, you get CtR, which self-updates itself sort of like modern web browsers.
A huge difference for business is that Windows Update allows you to approve/deny updates and cache them on a local server with WSUS, whereas CtR leaves each machine to go talk with Microsoft amongst itself on what to install and mostly cuts your IT staff out of the loop.
A huge difference for business is that Windows Update allows you to approve/deny updates and cache them on a local server with WSUS, whereas CtR leaves each machine to go talk with Microsoft amongst itself on what to install and mostly cuts your IT staff out of the loop.