How is a common emitter different from an emitter follower?
When we talk about common emitter, common base, and common collector configurations, the terminal that's named as "common" is the one that isn't used for input or output. It's the one that's used as a ground or "common" terminal by both the input and output of the circuit.

An emitter follower has input into the base and output from emitter of the transistor. It's a common collector circuit, not common emitter. 

A common emitter circuit has input into the base, and output from the collector of the transistor.

Whatever source you found that says that common emitter and emitter follower are synonyms is simply incorrect.