More recently you'd have, say, a 512GB SSD with 512GiB of flash so for usable space they're using the same base 10 units as hard disks. And yes, the difference

More recently you'd have, say, a 512GB SSD with 512GiB of flash so for usable space they're using the same base 10 units as hard disks. And yes, the difference in units happens to be enough overprovisioning for adequate performance.