Just because you say it with confidence doesn’t make it true. What’s your source? In the Lakewood vernacular it most certainly means that (which could explain the discrepancy in the ads).
I don't think a source is needed, however Google suggests Reb is "a traditional Jewish title or form of address, corresponding to Sir, for a man who is not a rabbi (used preceding the forename or surname).
'I never met Reb Zecharia'"
Whereas Rabbi is "a Jewish scholar or teacher, especially one who studies or teaches Jewish law.
a person appointed as a Jewish religious leader."
Of course in your locale, things may be different. But by default, Rabbi is not the translation of Reb.