I think the destiction between the two is basically to do with size. Horses are 14.3 hands and larger where as ponies can be up to and including 14.2 hands high. A "hand" is four inches. As usual, there are a few exceptions to the rule
.
Ponies are usually more stocky and more resistant to bad weather than horses, amazingly ponies are stronger. A huge Shire horse can pull its own weight but a Shetland pony can pull twice its own weight.
In your gallery submission of your horses Paul, you mention how well they look ( one looks pregnant to me) - which is exactly what I thought when I saw the ponies a bit muddy but healthy.
I would have thought that the ones in the wild are wild, if they had been kept previously, fed, stabled and groomed I doubt they would survive in the wild.