As mentioned before, ARM is the company whose designs all of these CPUs are based upon.
Apple, Samsung, nvidia, Qualcomm, TI, LG, and others license these designs and are at liberty to make changes to how they behave.
The differences between all of the dual-core versions from these companies is vast, not taking into consideration which GPU they use.
The Tegra 2, for example, doesn't have the per-core throttling that Qualcomm and others will probably have. This is probably a result of how quick to market the Tegra 2 was and how efficiently nvidia can produce chips.
It's all very fascinating, and I'm looking forward to owning an A5, Tegra 2, and MSM at the same time.
Well,it really isn't A8 nor A9.We could say Qualcomm has its "own'' architecture.The Snapdragon's first generation(HD2,Desire etc) was very very close to the A8.The second gen Snapdragon is more A9 than A8.Enhanced chipsets,faster memories,larger RAM etc are all part of it.And Qualcomm's were the only single-core chipsets that could boast this much.Overclockable @2+ GHz without getting fried?I am running my Desire HD daily @1.8GHz and it's stable,it doesn't get hot and it feels faster and smoother than everything I have laid hands onto.
I am very excited to see what the Sensation will bring.AND if it'll rival the Galaxy S 2.