Lost space on hard drive after OS change. What is it?

Question

Windows

Hard 500 GB, was Ubuntu, decided to go back to 7, and during the installation process, when dividing the hard into partitions, I noticed that 500 GB is the maximum possible, taking into account 460 GB system partitions. Nothing has changed in Disk Management after installation. I thought that there would be "unoccupied space in 40GB" but no. What is it and where did 40gb go

Answer 1

Linux uses IEC binary and decimal mapping, HDD respectively displays about 465 GiB and about 500 GB.
Windows "the old fashioned way" displays numbers in binary units, but with decimal prefixes according to the JEDEC standard, which misleads users.

Answer 2

My friend's 40 gig SSD was gone, just the paging file was included at the choice of the system;)
Maybe this is your case too?