It refers to those attributes of a system visible to a programmer or those attributes that have a direct impact on the logical execution of a program.
It refers to the operational units and their interconnections that realize the architectural specifications.
Examples of architectural attributes include the instruction set, the number of bits used to represent various data types (e.g., numbers, characters), I/O mechanisms, and techniques for addressing memory.
Organizational attributes include those hardware details transparent to the programmer, such as control signals; interfaces between the computer and peripherals; and the memory technology used.
For example, it is an architectural design issue whether a computer will have a multiply instruction. It is an organizational issue whether that instruction will be implemented by a special multiply unit or by a mechanism that makes repeated use of the add unit of the system. The organizational decision may be based on the anticipated
frequency of use of the multiply instruction and the cost and physical size of a special multiply unit.