The phrase "drive size" refers to the physical measurement or capacity of a storage device like a hard drive or solid-state drive (SSD). It indicates how much data can be stored on the drive or how physically large it is. Full definition
For hard drive size, the majority of gaming PC's use 1 TB hard drives, as do modern consoles. (gametyrant.com)
Both of the new models are available in 64 GB, 256 GB and 512 GB hard drive sizes. (techradar.com)
For instance, while hard drive sizes on the consoles are of decent size, they're not yet the hundreds of GBs one sees commonplace in PC computing, so there is a storage issue. (canadianbusiness.com)