An individual may have great influence for example and they may claim to speak authoritatively from a divine source. would this make them a personality cult or would they just be a personality.
A personality is just that . . . a personality. A personality cult is already defined (above) and is a group rather than an individual. A charismatic personality may still be an influential leader of a group, without it necessarily being a cult . . . but you then need to assess the behaviour of the group, and analyse whether or not control mechanisms are being employed . . . Behaviour, Information, Thought and Emotional control. All of the mechanisms are employed by using the psychological influences of guilt and fear . . . the prospect of losing salvation, losing reward, condemnation, disapproval, status, abandonment, isolation etc. In religious cults the concept of a utopian reward along with the concept of sin and condemnation, are powerful influences used to channel and restrict information, behaviour, thought etc. Black and white concepts (them and us, angels and demons, holy and unholy etc) remove the room for individuality, opinion or dissent, creating a contrived sense of willingness to conform. At that point, even flaws in ideology or doctrine become indiscernable for cult members. One of the easiest ways to identify a cult . . . is to hear the experiences of ex-members LOL.
I think you're right about Russel . . . his notoriety stems more from what his original church has become, rather than the kind of influence he exerted. He was open to dissent and discussion to some degree . . . and the following was largely willing, and free to come and go . . . but he did subtly claim special status . . . a theme that has run unbroken through the history of the Org. He still displayed, albeit innocently, the egotistical traits found in most fledgling cults. Cults are seldom formed overnight, but quickly or slowly, they evolve, as the benefits of greater and greater control and influence present themselves. Under Rutherford, we're looking at a full-on personality cult.
Hope this helps.