There is and there isn't. Your phone, almost certainly, with a shorter list of exceptions than not, has a locked bootloader and consequently cannot run unsigned software with full permissions without additional work. Sometimes that work is impossible to do. In terms of capabilities, sure, your phone is as capable, if not more capable than a desktop computer from a decade or two ago. The phone in my hand that I'm writing this from is 100 times more powerful than the computer I had as a kid. So that's an important point to make. However the specialness of phone silicon is the locked down bootloader and the downstream effects of that. You can point out exceptions where you can unlock the bootloader, but those are exceptions. The vast majority of phones you aren't going to get root on. So in that dimension, that's what's special about phone silicon. The signed chain-of-trust that is baked in and prevents you from running unsigned binaries with full permissions on phone silicon.