hi,
Well, Andy, it is question to Oxford Dictionary about difference of these two words.
For me, microprocessor has data bus, address bus and control bus/signals. Its task to execute (to process) program.
Generally, microcontroller has I/O ports only. Well, they may be configured as data/address/control lines OPTIONALY. The task of microcontroller is to control/check signals on its pins, order of external events etc. Indeed, microcontroller has a kind of microprocessor built-in. It may or may not be a program execution core (there are "hardware" microcontrollers known as automatic machine as well). Anyway, in ADDITION of event processor, microcontroller has some/many other things intergated like ADC, peripheral interfaces, timers etc. For example, microcontroller MSP430 (TI) has 16-bits RISC-processor built-in). in addition it has on-chip RAM, ROM, multiplexed ADC, some complex timers, LCD controller, etc. And I cannot call it just a "processor", can you?

Regards,
Oleg