Processor is the CPU that manages and runs software on top of it. In respect to Android, its refers to the Google's Android Operating System. There are various processors, notably ARM by Qualcomm, usually known as Snapdragon. Please use this tag if your question is specific to Processors.
The main manufacturer of the Processor or more commonly known as chip-set, is Qualcomm. Their line of chipsets is based on the ARM architecture, Acorn RISC Machine.
RISC is a Reduced Instruction Set Computing architecture where 20% of the processor instructions does 80% of the work. Unlike Intel platform, more commonly the x86 chipset, is CISC - Complex Instruction Set Computing, where 80% of the processor's instructions does 20% of the work. As it is now, RISC is inherently more powerful than CISC.
The line of ARM chipsets produced by Qualcomm, are known as the Snapdragon series, with two in dominance in the market:
- ARMv6, mostly found in budget smartphones - Snapdragon S1 (MSM7x27, QSD8x50).
- ARMv7, a more recent chipset that is powerful than ARMv6 - Snapdragon S2 (MSM7x30,MSM8x55).
Texas Instruments (TI) is another manufacturer of the chipsets used also, in similar principle to the lineage of the Qualcomm chipsets, their focus is rather more on, ARMv7 with powerful graphics support.