What's the difference between American red foxes and English ones (appearance wise, I guess)? What's the best/easiest way to tell them apart? They look really similar to me!
The most obvious difference is in the fur. European red foxes (Vulpes vulpes crucigera) have fairly short, stiff and densely packed guard hairs that are designed to protect them from wet weather. American red foxes (Vulpes fulva) have much longer, finer guard hairs, giving them that classic soft and fluffy look. Their fur is designed to keep them warm and protect them from the snow.
European foxes on the top/left, American on the bottom/right
American foxes also have much fluffier tails than European ones, often with rounded tail tips, while European foxes often have tails that taper to a point.
Another way to tell is the colour. Putting aside colour morphs, normal red coloured European foxes have a lot of different colours and tones mixed into the coat. Some can be fairly solid, but a lot have varying shades of red, yellow, brown, grey and black. Frosting, the silver guard hairs over the hindquarters, (and sometimes forequarters and face), and usually more prominent on European foxes. American foxes tend to be fairly solid in colour and don't have a lot of different colours mixed into the coat. The shade of red can vary depending on the subspecies, but the overall the colour will be pretty even.
As for colour morphs, the cross morph is only found naturally in American red foxes. There are a few regions in Scandinavia, Russia and Hokkaido, Japan where cross foxes can be found but those are all the result of farmed American foxes being released or escaping and breeding with native foxes. In the UK you will never see a wild fox with this cross colouring
In Europe the equivalent of a cross fox is the smokey or coal morph. They vary from a yellowish colour through to a dark brown with a lot of black and grey in the coat. Throat and belly may be white, dark grey or black, or a mix of all three and they lack the black faces of a cross.
Silver foxes do exist in Europe but they are exceptionally rare, and usually referred to as black foxes. They are often darker than American silvers with less silver hairs, although American silvers can very a lot in darkness.
Although this can vary a lot by region/subspecies and even individual, European reds tend to have quite blunt, rounded facial features. American reds tend to have sharper features, such as pointier muzzles and ears. American foxes are also smaller than European ones, but this is hard to tell from photos alone.
American red foxes also have longer legs than European foxes. This is most obvious when they’re in their short summer coat. European foxes also tend to have less black on the legs than American foxes.