In England, there are several kinds of bacon. broadly though, there are two - streaky bacon, and back bacon. Streaky is fatty and shrivels, Back has big crcles of meatiness in it. There are different ways of curing it which make a difference, and if you want great bacon in the UK, go to The Meat Like It Used To Be Co, 50 Cannon Lane, Pinner, HA5 1HW Tel: 020 88664611
In the US, they butcher the pigs differently, and you never get Back bacon, just very fatty streaky bacon that is halfway to being crackling. However, if you go to Cosentinos, you can sometimes find Irish Bacon (imported from Ireland, no less). Or you can buy it online by mail order, so you can make proper Bacon Butties (HP sauce is available in many supermarkets).
There is also something called 'Canadian Bacon' which seems to be a kind of circular ham, but is not a bad subsitute for back bacon.
But what happens to the missing meaty bits in the US?
They get sold as Pork Loin, which is a splendid thing to marinate and barbeque or roast, and usually good value.