From the inception of the “Plus CAL” in Lync 2010, there has been another radical change in Lync licensing now that 2013 is out:

There is no distinction for server licensing now, in other words, no more Standard or Enterprise version of the server, it’s now a single server license.  Still you have to buy a server license for every front-end only.

For Client Access Licenses, the same are still valid:

CAL

Features licensed

Standard IM, Presence, audio and video 1:1, desktop sharing
Enterprise Conferencing: multi-party audio and video, web
Plus Enterprise Voice

Enterprise and Plus CALs are additive to the Standard CAL. The Standard CAL can also be obtained from buying an EA Core CAL. You still need the client license (Lync bits/software) which can be bought either standalone or in Office Professional Plus.