In Asus Armoury Crate they must have changed the names for CPU settings but found this answer from a Reddit Thread:
SPL is "Sustained Power Limit". Also called PL1 on Intel. Its the power consumption the CPU should be able to maintain under load on a permanent basis. Only overridden if it runs into the temp target.
sPPT is "Slow Package Power Tracking Limit". Also called PL2 on Intel. Its the boost limit, lasting 28 seconds to several minutes.
Looks like Asus changed SPL to Platform sPPT but not really sure though.
I am taking a guess here but when it mentions "Platform" it could indicate the Motherboard's sPPT while the APU sPPT indicates the processor.
I would read Asus Armoury Crate Manual which should explain those two settings for the CPU.