The difference is getting blurry. Apus have generally better communication/latency/shared resources with the CPU.
The ultimate ideal of an APU is to have a unified memory with the CPU, which is the case in e.g the PS3/PS4
Despite progress in heterogenous computing (the neglected HSA), in SOCs, 3D ingerposers, high bandwidth buses interconnects and 3D memory such as HBM, the PC platform has yet to see a proper APU. In fact the M1 is probably the closest thing to an ideal APU on the market.
But yes the more time pass, the more the term IGPU denote APU.
AMD bought ATI because of the fusion vision, the idea that sharing silicon, resources and memory between the CPU and the GPU would be the future of computing.
An unrelated but very underrated is the egpu.
Egpus are external to the pc unlike a dgpu.
So you can buy a thin laptop, connect it via Thunderbolt to a rtx 3080 and enjoy faster gpu performance than allowed on any laptop on the market, and enjoy a thin lightweight, silent laptop the rest of the time.
Disclaimer Thunderbolt is still a moderate limiting factor in reaching peak performance.
Wat. AMD literally invented the term 'APU' and has been shipping them since 2011. Fully unified CPU+GPU memory since 2014's Kavari. That's full cache coherent CPU & GPU along with the GPU using the same shared virtual pageable memory as the CPU.
It's a spectrum. I don't think that cache coherency was useable by developers/compilers. The two only ways I know (HMM and HSA) are niche, used by nobody.
GPGPU compute would GREATLY benefit from programs that can share memory between cpu and gou without having to do needless high latency round-trips and copies.
So they failed in practice.
They never did a CPU addressable HBM interposer (despite having invented HBM) unlike what I believe is the M1.
> An unrelated but very underrated is the egpu. Egpus are external to the pc unlike a dgpu. So you can buy a thin laptop, connect it via Thunderbolt to a rtx 3080 and enjoy faster gpu performance than allowed on any laptop on the market, and enjoy a thin lightweight, silent laptop the rest of the time. Disclaimer Thunderbolt is still a moderate limiting factor in reaching peak performance.
Not just for laptops: this sounds also a bit like what the Switch dock could have been.
(And in some sense, it reminds me of Super FX chip for the SNES.)
APUs are AMD-speak for CPU and GPU on the same die (Intel has similar but doesn't call them that). Integrated graphics cards (a misnomer since there is no card -- IGP or iGPU is probably more accurate) may or may not be on the same die (instead could be on the motherboard, particularly in the chipset). That design is pretty rare/antiquated at this point though. Being on the same die means higher bandwidth, lower latency, etc.
