Well, except that the processing of the information off the sensor when doing DPAF seems to be a LOT faster with the R than with cameras such as the 5D Mark IV when used in LV. It probably has something to do with the additional processing provided because it is the primary means of using the camera for shooting still images, rather than a secondary one. It's all about the allocation of limited resources in size limited devices concerned with limited available energy and limited ability to get rid of heat. Or it may have more to do with the increased data throughput between the camera and lenses with the R system than the EF system.
However, more than a few folks have reported that when adapted to an R body, their most recent EF glass AFs faster than when attached to an EF body (recently introduced EF lenses probably have some firmware elements included to make them more compatible with R bodies than older EF lens designs - Canon has long included "hidden" capabilities in one piece of a system several years before the other piece is introduced: i.e. IS lenses first introduced in 1995 and the bodies beginning in 1993 that "secretly" included the firmware needed to run IS, or bodies introduced since late 2014 that have the ability to control the whiz-bang auto-aiming bounce feature of the 470EX-AI introduced in early 2018). This flies in the face of the assumption that more battery power is available to move focus elements when used with cameras with higher capacity batteries (such as a 5D Mark IV or 1D X Mark II) than when used with cameras with lower capacity batteries (such as an EOS R), as was almost always the case when comparing different EF and EF-S bodies.
I don't think my previous comment implied anything of the sort. Viewfinder based PDAF systems are fundamentally different than sensor based DPAF in several ways. That's what I stated. Imaging sensor based AF is not the same as dedicated PDAF sensor based AF. The context of my previous comment was with regard to a comment that states, "On most high-end dSLRs, you get center spot from 5.6 to 8 and nothing past 8." I was merely pointing out that several "high end" Canon DSLRs do, indeed, give more than just center point AF with f/8 lenses or lens/extender/TC combinations using viewfinder based PDAF. I then pointed out that imaging sensor based AF in LV is not restricted by the same maximum aperture limitations that viewfinder based PDAF is, and the limiting aperture for the same camera will be different when using LV than when using the dedicated PDAF sensor.
But beyond that, two different implementations of DPAF won't necessarily give the same performance in terms of speed and accuracy, even though the concepts by which they both operate are the same.