Hi Dan,
This X32 Wiki page almost answers your question:
Mix Buses, Sub Groups and DCA Groups - x32wiki
In their answer, they leave off "sub-" when they talk about groups.
The way you describe it,
"Look like they have 16 Bus sends on each channel. It appears they have combined the functionality of the previously separate into one"
isn't quite right, IMO; they have combined those separate functions into one area, in which you can choose to have each bus be one thing or the other or something else entirely.
The console has a total of 16 internal buses. Separately, there are 16 XLR outputs. There are also 8 Effects slots, which can be stereo, for 16 more things.
You can set up those 16 internal buses to be any combination of what other consoles call "Aux" buses, and you can set them up pre or post fader, either individually or in linked pairs. The linked pairs are only an odd channel and its adjacent even channel (1+2, 17+18, never 2+3 or 1+4 or 1+17 or whatever). This linking formula is true for inputs, too.
You can also have up to 8 effects, with 8 stereo returns (I think, haven't ever tried it) if you reassign some of the inputs to be FX inputs, either on the aux level or on either of the two 16-input levels. You can have up to 8 subgroups (I think, again never tried it, maybe you can have more??).
Any output bus can be assigned to any XLR out. You can also pick direct outs from any of the input channels to put on the XLR outs.
The limitation is that you can do all those things, but you can't use more than a total of 16 internal buses, 16 XLR outputs, and 6 TRS Aux outs. You can configure it almost any way in which those limits are not exceeded. There are many more than 16 signal choices to assign to the XLR outputs, for example, but you can't use more than 16.
Does this help?
I've said several things that I've never tried, so undoubtedly experts will chime in to agree or correct.