imo the main physical difference between the rpi and the pyra is that one is a sbc board and the other is a handheld (tada!).
in a handheld type computer one really needs a lot of functionality embedded, as it has to be somewhat selfcontained so one can hold it... in the hands.
so this makes a handheld initially more complex and costly as an sbc board, where one can add things externally without caring for this handheld factor.
if i remember correctly, hardkernel wanted to buy this soc from the rpi foundation/broadcom for a wearable odroid, and they did not sell them any.
what i do not like about the rpi foundation is that for the rpi2 and above they stopped releasing schematics and the bootloader is still closedsource, i think.
having said this, i still like my rpi2 alot and i'm using it as my current main wall-powered homecomputer.
i also have a rpi3 but it's still in it's cardbox as i dislike to use a fan to make it cool enough for long compute-sessions without constantly throtteling down the speed.
that the development of the rpi is not communicated in their boards is not really great too imho.
a new supersecretly developed rpi gets released, but without community involvement in the design and no eben upton writing in his own boards, unlike ed
who makes polls about colors and whishes and is a supernice community host all around here on these boards who really cares.
i whish the rpi foundation all the best, but for the future i like the pyra to be my main wall-powered homecomputer and handheld in one system.