It's your everyday SPI.
"Your everyday SPI" being, it can be anything. There is no single, clear, well-defined SPI. SPI generally means a "type" of communication, details vary.
Be thankful it's 16 bits. Weird bit counts (anything goes, like 13 bits) are usual, and not all MCU peripherals support all possible bit counts; most modern and advanced can be configured like for anything from 3 to 32 bits. Of course, you can configure the MCU in either 8 or 16 bit mode, in latter case you'd get only one interrupt / DMA request per packet which is of course desirable.
Play with Clock Phase and Clock Polarity settings until it works reliably. There are just 4 combinations.
The name can be anything. Maybe it's a trademark thing, or just tradition. It can be ASDFGH, but the distinctive features of SPI are:
* Packets are delimited by nCS. High->low transition starts packet; low->high transition ends packet
* Data is clocked synchronously using a clock signal
* Clock signal is active only when nCS is active.
It gets confusing when the manufacturer throws the Scrabble tiles on the table to coin the new name for their SPI, and it happens to clash with something that already exists, like we can see the SSI confusion above.