I would say yes: the things typically billed as "microcontrollers" are almost always just a variant of some other CPU: 68HC11s are just a minor variant of Motorola's 68xx series, in terms of instruction set.
Microcontrollers typically have some extra hardware on them, like timers, clocks, maybe a small amount of RAM, and some EEPROM. They usually also have some extra inputs, maybe like an Analog-to-Digital-Converter or two.
The idea behind "microcontrollers" is that a lot of things can use programmable control. Microwaves, washing machines, ovens, alarm systems, but they really don't need big programs, and the designers of those systems don't want to add an entire "computer" to them. So you have a microcontroller with the simple program in EEPROM, and a small amount of RAM for a stack or what have you. The extra timers, clocks input ports, ADCs, etc, let the appliance designers do away with other discrete components they'd almost certainly have to stick on to do any useful work.
A lot of the old 8-bit CPUs had "microcontroller" variants: 6809 is the "computer" variant corresponding to the 68HC11 microcontroller. 8051 is the microcontronller variant of the old 8080. See: http://en.wikipedia.org/wiki/List_of_common_microcontrollers
