What is the difference between core-based and user-based licenses

2.3.1 User-Based Server License:  If your Server Software license is designated as User-Based, the Named Authorized Users enabled to use such Server Software must not exceed the number of licenses purchased on the Invoice or specified at the time of purchase.  If your User-based Server Software license is designated on the applicable Invoice or at the time of purchase as Guest Authorized User enabled, for each such license you may enable an unlimited number of Guest Authorized Users. 

2.3.2 Core-Based Server License: If your Server Software license is designated on the applicable Invoice or at the time of purchase as Core-based, for each such license, an unlimited number of Named Authorized Users may use the Server Software, provided that the total number of Cores residing on all computers where the Server Software is installed does not exceed the permitted number of Cores identified on your Invoice or at the time of purchase.  When the Server Software is installed and distributed across multiple computers, all the Cores in each of these computers count toward to the total number of Cores licensed  by you and indentified on your Invoice or at the time of purchase.  "Core" means the processor or execution core contained in the same integrated circuit within a computer’s central processing unit, whether such Cores are virtual or physical. If your Core-based Server Software license is designated as “Guest Authorized User enabled”, for each such license, you may enable an unlimited number of Guest Authorized Users.