Cortex A/R/M

The Cortex family of ARM processors provides a range of solutions optimized around specific market applications across the full performance spectrum.
Cortex underlines ARM's strategy of aligning techna-ology around specific market applications and performance requirements.     
The ARM Cortex family is comprised of three series, which all implement the Thumb-2 instruction set to address the increasing performance and cost demands of various markets

ARM Cortex-A Series,
        Applications processors for complex OS and user applications.  
        Supports the ARM, Thumb and Thumb-2 instruction sets.
ARM Cortex-R Series
        Embedded processors for real-time systems.  
        Supports the ARM, Thumb, and Thumb-2 instruction sets
ARM Cortex-M Series
        Deeply embedded processors
        optimized for cost sensitive applications.
        Supports the Thumb-2 instruction set only