I think the current accepted answer is a bit misleading, so I'll chime in a bit.

Indeed UC stands for Unified Communications. However, Microsoft Skype for Business is also a UC solution – as much of a UC solution as any other supplier's UC solution, such as Cisco's. So why do headset and speakerphone manufacturers produce generic UC and Microsoft compatible versions separately?

One is the button implementation. Depending on the specific buttons, the buttons will respond differently. Standard volume up and down will work as usual, but special buttons have different implementations (only the Skype for Business app responds to some).

Second is detection of the correct sound device. With the MS version, Skype for Business will always choose that device for the communication device. This is important for IT as the end user might be plugging in separate headsets for playing music etc., but Skype for Business will always default to using the correct headset/speakerphone (unless set otherwise).

Basically we went with MS certified in the Lync roll-out (nowadays Skype for Business) specifically for the correct device defaulting (ie. less IT support work), even though simple UC standard headsets work identically (if set up correctly).