Functional
When the bread is toasted, it pops out of the toaster.
Operational
Users should clean their toasters weekly, not stick forks in them, and bring the toaster in for repair when they emit black smoke.
Technical
The toaster will be built using tungsten alloy for its heating element. The outside shell will be stainless steel.
Functional requirements explain the function of the product. What is its purpose, what does it do? What will people use it for?
Operational requirements explain what human action is needed to keep the product operational. Maintenance, observing and fixing issues, ...
Technical requirements are product build decisions. The user doesn't care about those, but the product builder does.