Enthusiasts may have greater knowledge of the railway as a whole, but in specific areas staff often know more. I guess you could see it as though the enthusiasts are the 'jack of all trades' while staff are often the 'master of one'.
I'm not sure I'd agree with that.
Many enthusiasts will have very extensive knowledge precisely because they don't have an obligation to know about other things. A 'train-spotting' enthusiast may know about every class of train under the sun, and the routes they are used on, but doesn't need to know anything about ticketing, health and safety, the geography of railways. By contrast, a member of staff in a generalist job such as a guard doesn't need to know about stock on other TOCs, but does need a decent knowledge of geography, ticketing, health and safety, 'interpersonal skills' etc. An enthusiast has the luxury of only engaging with the bits that they are interested in! On the other hand, some staff with very specific roles (most obviously drivers/engineers) will have access to a wealth of information not available to non-rail people, and don't require any particular knowledge of certain areas (Eg ticketing).
In other words, I think it will vary from enthusiast to enthusiast, employee to employee, and job to job.
I'm reminded of an interview I heard last week with Metallica. They were saying that when they make a decision to play an older song on tour, they have to relearn it, often going onto Youtube to watch videos of fans playing their work. They have to learn it back again from enthusiasts! I think in any field with fans/enthusiasts, there'll be specific bits of information that they know better than the practitioners, but only because they don't have to focus on the wider picture.