Could you please post the model number of your system? And I will take a guess here. The HD+SSD is the same drive. The second designation applies to the cache drive that is part of the HDD. So you will be installing programs on the C: drive as that is probably the main drive.
Its a G7 15. 1tb +256gb SSD.
The C: is the main drive but it only has (223gb) the 😧 (931gb). I should install on the C: for better efficiency? Or there's no difference since its only cache and - as I read in various sites - its automatically alocated?
Go to Windows Disk Management. The lower half of the main (center) area will show you which partition(s) are on which physical disk. It's likely that your C drive is your SSD and your D drive is your spinning hard drive.
I got it. Entered by another path and C: is the SSD. Do you know if I can use intel optane in both partitions?
Not sure how I missed this, but are you sure your system has an SSD, an HDD, and a slot for an Optane card? Even if it does, my understanding is that Optane is only used for spinning hard drives because it doesn't make sense to use an SSD to accelerate another SSD, in fact if the "real" SSD is faster than the Optane module, Optane would actually create a bottleneck.