S/X both have SSD's. PS5 SSD is almost twice the speed but the difference shouldn't be too pronounced. The Xbox storage is roughly 40 times faster than the previous generation consoles, so a difference of two times between Xbox/PS5 is going to seem minor by comparison.
Old HDD Consoles = ~120mb/s
Xbox Series S/X = 2400mb/s (raw), 4800mb/s (compressed)
PS5 = 4500mb/s (raw), 7500mb/s (compressed)
It's actually 5.5 GB/s (raw).
I should have double checked the compressed number earlier as well--it's 9 GB/s.
Sony, if you're reading this, do something new with The Legend of Dragoon. You will make me a happy man. Thanks.