Unlike the Windows client (of course!) the Mac S4B client is in fact a complete re-write compared to Lync for Mac. It is still horrible, in different ways (of course!) than the Windows client, but generally is a modest improvement on Lync for Mac.
Windows Lync>Skype for Business is literally a registry key you roll out that changes the name and some minor interface chrome.
Windows Lync>Skype for Business is literally a registry key you roll out that changes the name and some minor interface chrome.