The Cell processor is much different than a PC processor. The 360 processor on the other hand is extremely similar.
The XBOX 360 and PS3 chips are both from IBM, both PowerPC chips, and have a incredibly similar architecture. The difference is that Sony included a set of SPEs that are of dubious value for most game software.
I recommend you read the book "The Race for a New Game Machine" by David Shippy and Mickie Phipps.
The basic story is about how Microsoft was able to get IBM to sell them the chip that they designed for Sony before Sony got their hands on it.
From the book summary:
Now Chekib Akrout, IBM's senior vice president responsible for the PlayStation's chip team, told me another customer wanted our secret-weapon, record-smashing PowerPC microprocessor core. It was Microsoft.
"How did this happen?" I grumbled through gritted teeth.
"Let's just say it was a blockbuster, an offer IBM couldn't refuse," he answered. Over a billion dollars were involved, spanning the entire spectrum from development to chip manufacturing.
"There's more," Akrout said. "Microsoft wants something very similar to what you designed for Sony but with some unique enhancements, and they want it on the same schedule." He then described the design changes Microsoft needed for a super-aggressive, market-shaking Christmas launch.
Akrout didn't blink. It took me a second, but I got the message.
Let me give you the executive summary: the CPU in the PS3 and the CPU in the XBOX 360 is practically the same chip.
Sure, Microsoft went with a SMP design and Sony instead went with six "Synergistic Processing Elements" (well, eight, but one of them is unavailable to games and one is disabled for yield reasons). My point is that neither is very much like a x86 PC in the CPU department. Not even close, as I outlined before. Saying the XBOX 360's PowerPC chip is "just like a PC" and that the PS3 is somehow different in this department is comedy to anyone who is familiar with the details.
On the GPU front, the XBOX 360 has a custom GPU that never shipped for a PC. The PS3 has a NVIDIA GeForce 7800 GTX (NV47). Which one of those is more like a PC?
Finally, people say "being like a PC" as if it's a bad thing. The PS3 is like a PC in many ways that are great!
Here are two that come to mind:
- You can use off-the-shelf PC peripherals (keyboard, mouse, etc) on the PS3 and not the XBOX 360
- You can use off-the-shelf PC hard drives in the PS3 where Microsoft requires you buy their branded drives (boo!)