Are Hyperthreaded Cores Seen Differently?

In Intel's implementation I thought that the purpose of hyperthreading was that if you have a processor with x cores the OS would see the processor as having 2x cores. But it's clear from the community, and whilst watching WTask Manager whilst playing games, that only x cores are utilized at a time.

So I'm just wondering if the hyperthreaded cores are somehow seen differently, and if so why games choose to ignore them.

I remember having to go into the config settings of GRID and manually add additional cores to get it to use them. Is it possible to do that with other games?

Thank you.