What storage slots does the m15 R4 come with? I see Dell says it supports one of several configurations, but does that mean there are multiple different laptop chassis with more or less storage than others, or does that mean that those are all of the different mix and match ways I can have storage set up?

I saw that the m15 R3 supports

"There are three slots for M.2 PCIe Gen3 x4 NVMe solid-state drives. 
Slot 1 supports M.2 2230 Up to 512 GB or M.2 2280 Up to 2 TB. 
Slot 2 supports M.2 2230 Up to 512 GB or M.2 2280 Up to 2 TB. 
Slot 3 supports M.2 2230 Up to 512 GB. "

On another post, is this the same as the m15 R4?

Thanks in advance