Architecture

An architecture defines behavior that is common to many processor designs.

Processor
A processor is an implementation of an architecture, and can be integrated into several different designs.

Device
A device contains a processor and additional components.

the information can be divided between several documents:
    • the architecture reference manual (ARM)
    • the processor technical reference (TRM)
    • the device documentation.

Architecture
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The ARM architecture defines how an ARM processor must operate. This includes:
    • the programmers model
    • the instruction set
    • system configuration
    • exception handling
    • the memory model.

ARMv7 introduces the concept of Architecture profiles, defining versions of the architecture aimed at different types of processors for different market segments.
A  The Application profile defines a VMSA based microprocessor architecture. It is targeted at high performance processors, capable of running full feature operating systems. It supports the ARM and Thumb instruction sets.

R  The Real-time profile defines a PMSA based microprocessor architecture. It is targeted at systems that require deterministic timing and low interrupt latency. It supports the ARM and Thumb instruction sets.

Processor
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A processor is implemented to comply with a defined version of the architecture. For example, ARM926EJ-S™ implements ARMv5 with the TEJ extensions, and Cortex™-A9 implements ARMv7-A with the multiprocessing extensions. 

Device
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A device is usually a SoC that incorporates an ARM processor and additional components. At the time of device implementation, options such as cache sizes, floating-point hardware support can be selected. This means that different devices based on the same ARM processor can have different cache sizes.

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When you design or develop your system, there might be three or more different sources of information that together describe the behavior of your ARM target. Depending on the nature of your question, you might have to combine two or more of these to cover all aspects of a specific behavior.
For example, if investigating a memory corruption problem on a target, you might have to combine information from documentation that describes:
• the architecture
• the ARM processor
• the device
• the bus interconnect used in the device
• the external cache controllers
• the memory controllers
• the memory devices.