A CPU can have multiple kernel, which is the real physical core, and often the processor with Hyper-Threading technology, which will each core can be divided into two threads, and threading is provided on the basis of two cores on a single logical processors, the use of special hardware instructions, the two logical cores modeled as two physical chips, so that two physical core four threads, will form four logical processors. Now generally say how much nuclear usually refers to the number of logical processors.
Reference article: Relationship distinguish cpu, cores, and logical processors ask
