The drive manufacturers quote in decimal -- 1 decimal meg = 1000 bytes Windows counts in binary -- 1 meg = 1024 bytes. You lose about 7% of the decimal value, so you see about 476 G.   The space you see used is consumed by UEFI setup, recovery partitions, a system image and the operating system.  
Anyone knows why in my settings shows that my notebooks has a total memory storage of 457 GB, although I bought a 512 GB.  The app My Dell shows 512 GB, but Windows shows that it came with only 457 GB, and 111 GB already was occupied. So actually I only have 345 GB available. Anyone can explain me why is that, and if is it correct, please?
Less memory than I bought