Since Android really took off, Qualcomm's name has become ubiquitous when talking about smartphones - they make the best chips and have done for some time. Whilst there was some competition from nVidia and their Tegra line, when it comes to pure processing power, Qualcomm's Snapdragon processors win out every time. This has been no more true than it has this year, 2012 has definitely been Qualcomm's year, thanks to LTE. Pretty much every high-end phone that has come out this year packing LTE has had a Snapdragon S4 at its heart. Not only because it's one of the few chips that support LTE right now but, also because it happens to be pretty damn fast.
There's been some confusion over this, because it's a 1.5Ghz dual-core chip and the Tegra 3 is a quad-core at 1.5Ghz - as is the Exynos 4 quad. So, why is the S4 even comparable - let alone a little faster - with what only seems to be half the processing power. Well, this is done to newer technologies emerging on the ARM platform - which you can read a history of here.
The S4 line of processors are based upon the new Cortex-A15 core from ARM, whereas the Exynos 4 quad and Tegra 3 are based on the older Cortex-A9 core. The sort of leap in technology we're talking about here is say a 2nd gen Core i3 vs a 1st gen Core 2 Quad - one looks better on paper but one is certainly a better performer. Of course, CPUs aren't everything as tablets and smartphones run on SoCs - Systems on Chips - bringing a whole system together on one chip for a phone or tablet to get everything from. So, that's your CPU, GPU for Games, WiFi, Bluetooth etc all on on one chip.
The Snapdragon S4 Pro from Qualcomm is coming to market with power in all the right places, for one, it's running 4 cores at 1.5Ghz and when these cores are Cortex-A15 cores then you know this thing is going to be crazy fast. However, processing power isn't the be all and end all, if you've built a PC with a super-fast CPU but a poor graphics card you know what I'm talking about. Adreno graphics from Qualcomm aren't exactly the best but they're perfectly capable and with the improved Adreno 320 in the S4 Pro games should run like butter no matter what detail you have it set to. This is all quite exciting because for the first time, mobile processing is seriously catching up to mainstream Desktop computing - sure, these things are no Core i5 or i7 but will these SoCs fill the gap that laptops are beginning to leave? Of course they will - I've been holding off on upgrading my tablet for this specific reason - I want Cortex-A15 and I want quad-core. My tablet is my laptop and why wouldn't I want a screaming fast tablet?
There's a lot that Qualcomm are offering manufacturers with the S4 line and below you can take a look at this chart to see what each S4 SoC can offer: