[kapital]

Is the only difference between promotor and operon that operon regultates expression of more genes?

[Yggdrasil]

An operon is a region of DNA containing a promoter, an operator, and a set of protein coding regions that are transcribed to create a polycistronic mRNA (an mRNA encoding multiple proteins).

A promoter is a general term for a region of DNA that influences the transcription of a nearby protein coding sequences.

[Wreath]

They are two different things.
Promotor is sequence which is part of each gene, or transcription unit. It contains some conserved sequences, which are different for each species.
Operon is special transcription unit, which is controlled by concentration of the substance which is influenced by the gene. For example, Trp operon is controlled by the level of tryptophane in cytosol. Lac operon is controlled by concentration of lactose and glucose in cytosol.
Hope that helps.