I think that is a bit unfair to say that you can see the difference between professional and non professional pictures . Most of the public are miles away from the track behind wire mesh and unless they get there early are behind a lot of people . I was reading a bit in an article about a football photographer saying that he used 2 cameras and out of 200 shots would only use 10. Sometimes the non professional photographer may be lucky in capturing something which nobody else saw . Sometimes it is the luck of the draw .
It really does depend on the circuit. I did a ten year stint as a pro, shooting mainly at Rockingham, Snetterton and Brands, plus assorted meetings at Silverstone, Donington and Lydden. And short ovals.
At some circuits (like Snetterton before it was... ruined) you could actually get better shots from the spectator banking than from the fenceline, especially at Coram and the Esses. Silverstone was shite regardless, because even with a media pass, you're still half a parsec away from the action, and you really need a 300 2.8 with stacked converters to get close-ups. Brands is one of those places where an amateur can get really good photos (although it's harder these days with the wire fencing), and likewise Rockingham, especially when standing on top of the pits garages.
Admittedly, the definition "amateur" covers a fairly broad spectrum, and I started out as an amateur who got noticed. I came second in a national motorsport competition with a shot I'd taken with a disposable 35mm camera, hanging over the gate behind the pit lane at Snetterton. There are amateurs who do some serious photography, and their stuff is pro-level - the boundary is blurred.
But I'll definitely agree with
@Gravity Aided - us pros generally have better kit and a better understanding of the kind of shots that are commercial, especially when it comes to cars out on the circuit. I started out my career in the media shooting film, but switched to digital very quickly purely from a financial / operational standpoint.
Though in my archive, I do have a fair few amateur pit & paddock shots that I really like. The portraits especially, because people are posing for the fans, and they do tend to come across far better than the portraits you see in things like press packs, which make the subjects look like they've been sent to a taxidermist.
Having said that, I was largely known as a pit & paddock specialist. I loved nothing better than to stick a long lens on, lurk in the background and people watch. Or sometimes, stick a short lens on and... No, never mind...
Anyways, I hope this helps you understand what I mean.
