I been here since this thread opened up and going to weigh in a bit.
What discrepancies are there between Bronies/Horsefuckers (lord knows they try to say there is a diffrence betwen a bronie and Horsefucker) and a Furry?
Well they are both claiming to be Fandoms which like or have admiration for content which includes anthropomorphic animals.
They both have conventions which are held through out the world and held annually.
They both have a few which cosplay, some even in full costume.
Both of their cores revolve around the internet.
Innocent enough right? But where they begin to break off is what vastly defines both groups and separates them greatly. First of all the term powerlevel comes to mind, as this is a term used to define one's admiration for the fandom or hobbies they enjoy. We see things like tee-shirts, hats and other clothing and what difference is there here between wearing this an any other MLB/NFL pro sport paraphernalia? You would glance at it once and be on your merry way. For a few others, there might be a sticker on the bumper showing the same admiration. For furries on the other hand, it isn't just some brand logo they are showing off, it is a statement which they must shout from every rooftop.
Every message that the furries state must be towards their lifestyle and sexualized. Two animals humping each other, gay pride flags with paw prints on top (what are you saying, you are a gay furry or you want to include bestiality in the LGBTB?) They use words like Yiff to signal sex because they believe it is the sound a fox makes when he is having sex. Everything is overly sexualized and everything has to be in big bold letters so everyone can see. If you find it disgusting, degenerate or appauld by it, they coin their own term Furrsecution (Persecution) as if it is supposed to mean anything. When they don't get their way, they scream as loud as they can to make sure everyone else knows that you told them to fuck off.
Wearing animal costumes isn't something they do only at conventions, it is a life style to them and they make sure others know it. They go to malls, bowling alleys, and other venues. When told to take off their masks, they howl like wild animals and defecate on the floor before storming out. In a post 9/11 world, it is alarming to anyone that is fully covered head to toe no matter how "innocent" they appear.
When not in full costume, they choose "pet play" and bondage gear. Collars, leashes, walking around on all fours and wearing leather masks. They are practically wearing nothing but a harness and nearly fully exposed in public, but they don't care, in their eyes, they are animals.
I never seen a bronie or horse fucker not pretend, but believe that they are some magical unicorn, nor have I seen one that believed they were to be called out on their shit and take major offense and defecate in protest.
You get perversion no matter where you go, you get cringe too, some serious others just being jackasses to win some "internets" as a gag. Both can be seen as having a degenerate side to it. But just like how the LGBT community claims to be a lifestyle, so does the Furries. It is apart of who they are, and if you don't accept then you are some bigot, raciest or fascist. They lean highly left, any right group is just a gag but even they are outed by the majority. It has become a forefront for Anti-Fa and recruiting because of the highly left ideologies, the majority who are with in the LGBT community and how many use it to justify violence for not accepting their lifestyle as being "normal".
I can't attribute the same to the Brony fandom no matter how much "cringe" I see, I never see the same level of belief nor devotion to belief as I do with furries. Furries can't distinguish fantasy from reality and is the biggest discrepancy between the two. Bronies see that what they like is just a cartoon and for the most part understand it is a fantasy.
If you really want to know more about them psychologically however, look up the University of Waterloo who has been researching them for a long time along side bronies. Furries are really the most insane of the groups. I can't say when they started their research but it is still ongoing and I remember starting to follow them back in 2013. If you want first hand accounts of the furry fandom, even though largely anecdotal, I will be more than happy to share my stories.