Apple's PowerPC CPU's were absolutely their own design. They formed a consortium with IBM and Motorola, and both of those companies acted as Apple's foundry for CPU production.
There are myriad differences between the IBM x86 architecture and the Apple PowerPC RISC architecture. I had the opportunity to run identical engineering programs on the two architectures, side by side. The RISC machine blew away the x86 machine. So the move by Apple to x86 involved far more than "merely switching" to Intel.
Intel's production methodology is more efficient, prompting the switch. But in doing so, they lost the computing edge, and use the same CPU's as everyone else. They just try to cover it up with their operating system. So now, it really does not make any difference, because the foundations are the same.