The feature updates for Office 365 ProPlus are managed in a similar (but not quite the same) way as for Windows 10.

There’s a Current Branch and Current Branch for Business, but no Long Term Servicing Branch – if you want a static version of Office then you’ll need to deploy Office Professional Plus 2016.

There is, however, a First Release for Current Branch for Business to give organisations a chance to evaluate the CBB build before deployment.

There are some good explanations and diagrams in this TechNet article – it’s definitely worth a look: http://bit.ly/1Ov0l8Q.