Well, actually, no. Barns are not always alike . But they have a certain function - they are where they store the hay, and the corn to be threshed. So they tend to look more or less the same at first glance, just like a garage is a garage, and is where you put your car. Old barns in today's world are sometimes used as machinery sheds, or converted to animal stalls, and if in the right place and not needed any more, they can even be converted into desirable residences for yuppies .
What you see in this picture, which was taken in Jane Austen's Hampshire, is the kind of farm that was built after enclosure, when the land was divided up and the farmer built something close to his fields rather than continue to house himself and his animals within the village. It's the usual three-sides-of-a-square arrangement, and you can see the barn, all black, at the back. The "front door" of the barn sticks out- it's very large, to acommodate a loaded haycart . The cart would be taken in through the door, unloaded, and then taken out the other door on the other side of the barn. This "out" door would be smaller, because the cart would be empty. Why two doors? Well, if you've ever tried to turn a team of eight oxen- or even two horses- in a confined space with a heavy wagon behind them, you'd know why!
That funny building in front of the barn is a granary. This is where threshed grain would be stored. The mushroom-shaped staddle stones on the "legs" of the granary were to keep the grain dry in wet weather and also to keep out vermin. They'll usually tell you it's to keep out rats, but rabbits squirrels , weasels and other small animals might well be interested, and baffled, by the granary. Human access would be via a removable wooden ramp up to a raised door- which you can't see, of course, in this picture!
Granaries like this are not a sign of an 'enclosure' farm- they date back to an earlier time. Indeed, there's one in the village where I grew up with is seventeenth century or older. With my usual sense of timing I didn't find out about it until I grew up and moved out!
This photo is another one from geograph.org. uk. The farm is in Hannington, Hampshire.