I think since it’s internal that 16g isn’t comparable to 16g.
Talking about speed, I'm sure it is faster with internal RAM. And it may feel like more than the same amount arranged externally. From a storage standpoint, it will be the same whether it's internal or external. You have 16GB to store your open applications and files. Once that space is filled up, the OS has to start swapping pages out of the RAM and into more permanent storage (HD or SSD) to make room for other files or applications you want to load. All those CPU cycles are essentially wasted, because no real work is getting done. It's not as common anymore, but if memory is too limited for what you're trying to do, you end up thrashing, which is where the CPU spends all available clock cycles on swapping. So if 16GB isn't enough for a user now, moving it onto the chip probably won't make a huge difference. I'm sure it will speed up swapping, but it's better to simply avoid it in the first place because all you're doing is slowing down the computer.