Mainly, Computer Architecture is the rules and methods which describes the functions, capabilities, programming model and implementation of a computer system. Whereas, Computer Organization is the interactive combination of hardware programs and users. 

The study of Computer Architecture and Computer Organization helps to know the execution of computer instruction at the micro level and it knowledge helps to write programs faster, smaller, less prone to error. It gives idea about relative cost of computer operation, the relation of software and users by their inner working