Threads are (sub entity) of the cores (tree level progenies hierarchy)
For the operating system , the word threads, could represented the others signification.
To vulgarize grossly ......
1 System (kernel)
2 (drive affinity cores)
3 forks ( child sub core)
4 forks (pids or sessions)
5 threads (child of pid)
(For the kernel , Semaphores are agents driving all tasks with the rules policy)
With all the operating system recent, more you have cores and threads, more results
also all new softwares must take in count now this evolution.
To extend or see more concrete
Open this link as example
open this title section
3.10 GOMP_CPU_AFFINITY – Bind threads to specific CPUs
(I finish, i am interrupted busy previously)
Within a session (pid or fork), the access of affinity for programmer is:
physical processor when you have several elements on mother board, his specific core,
and finally the threads.(very large number possible).
When you have only 1 physical processor with 2 cores it's the same process , just you have level
2 (specific core) are moved to level 1 (as pseudo physical processor)
It's also same with threads cores
Processor Number N570
# of Cores 2
# of Threads 4
You have only 1 physical processor, but for your system,the convention is simplified;
you have four pseudo processors are accessible.