...the difference between a 'fan', and an Objectivist?
There are many differences.
First and foremost, Objectivists almost never use the term 'Objectivist'. In fact, the vast majority of them don't even know the word.
They merely apply rational judgement to the world about them, and reason their way through all the traps being sprung by the fever wards.
Fans, on the other hand, are never satisfied with the products of such minds, and only accept them grudgingly after they have done them down because they don't sound like an identical quote from one of the less elegant passages which can be found in the works of Ayn Rand; that is, they can't find the familiar hints that they have used to wear out a neural pathway to their tenuous hold on the truth.
Fans will witness a maestro of reason and wit producing a master work and yet will reject the work, or worse still the author, because they haven't polluted their work with unnecessary affirmation of someone else's expression.
In other words, fans, those fanatics of rote dogma, reject such people because of their integrity.
Because they are actual people.
And all the while, the rational go on being Objectivists in the same way that weights go on being 'gravitational', while they are on Earth.
It goes without saying that there are large numbers of liars and charlatans as well, but because fans have abandoned rational judgement for rote dogma, they cannot tell with any certainty.
So the cheats rattle the dog's bowl with the 'O' word and mention of Rand, and enjoy the spectacle of salivating fans who bark with their votes.
And the Objectivists are to be found elsewhere.