Well, those are threads not physical cores.
To put it simply, a thread is a single line of commands that are getting processed, each application has at least one thread, most have multiples. A core is the physical hardware that works on the thread. In general a processor can only work on one thread per core, CPUs with hyper threading can work on up to two threads per core. For processors with hyper threading, there are extra registers and execution units in the core so it can store the state of two threads and work on them both.