In the PC field the Processor & Microprocessor are synonymous. Basically it is the brain of the PC which carries out all of the low level "processing" that the PC needs to do - calculating the sum of 2 numbers is a simple example of something that the processor will do. Basically every single task that the PC performs is dependent on the processor doing its stuff.
PROCESSOR
Meaning of PROCESSOR in English
English glossary of Internet and PC terminology. Английский глоссарий Интернет и ПК терминологии. 2012