Alternators and Generators

An alternator is a synchronous generator. A sub-set of the generator family.

Other generators may be DC, Induction,....

Alternator is "Alternating Current Generator" - it can generate only alternating current whereas a generator can generate either DC (if is a DC Generator) or AC (if it is an alternator)

Alternators are a special type of generator.

The Name "Alternator" is precisely mentioned for the special type of generator, of which, producing alternating current.

They produce only AC . The main area of use for an alternator is producing power.

Generator is a large classification. In electrical terminology, Generators are generating any type of electric. Alternators are very suitable for power production, therefore other generators are used for different purposes, such as metering (Tachogenerators), Some use for DC welding, etc.

All above mentioned alternator and generators are Rotational machines.

Some other semiconductor based devices are also called generators.

They are solid state,but not rotational. They are generating different types of waveforms. Such as square wave or sinewave, or a ramp generator form .

Just to remind Induction generators don't fall under alternator category.