Originally Posted by raverx3m
why would they not use internal usb port then if its faster than internal drive bus?
makes no sense
am I behind the times then? I thought the sata interface was always faster than usb
how can external interface be faster than internal it seems backwards
why would manufacturers use an interface that's slower when faster one is available?
Xbox One and PS4 both use SATA 2 interfaces for cost savings because 5400RPM drives don't even saturate SATA 1 interface. On the PS4 and PS4 Pro the front two USB ports share the same interface and power (think 2 ports plugged into one) also for cost savings. Luckily if you have a PS4 Pro it has a 3rd USB 3 port in the back that is it's own channel and power source (direct to board).
Point 2 is file system. These consoles are geared to run/load/etc off a slow 5400RPM drive that needs to access certain areas of a platter at a specific time and therefor is partitioned specifically for this reason. If you take the drive out and put it on a machine with Partition Wizard or Macrium you can see this weird partition system that their file systems are geared for. This is why SSDs internally don't grant that much of a performance gain. External storage devices on the other hand aren't formatted that way, at least not as sporadically which is why SSDs have better performance on the USB port. Not only that, but USB3 is faster than the internal port and because of both points the speed of the SSD is limited only by the CPU.
I have a 1TB 860 Pro in my Xbox One X and a 512GB Micron (Crucial) internal in my consoles. Having the SSD external does make a difference in both consoles. Does the system UI load quicker and seem snappier with an SSD internal? Yes, but at the cost of a slower loading performance in games vs having it external. That's why I do external and internal SSD in both. Luckily, this won't be a problem anymore with the new consoles coming out this holiday season as they both have NVMe 1TB drives internal.
One additional point, the performance increase isn't as drastic as you'd see on a PC. It's a subtle difference, like seeing myself load into a map faster than anybody else in BF1 or CoD but doesn't feel as fast like on a PC.