Bacon is a staple part of a cooked breakfast on both sides of the pond. However, there are some very important differences between British and American bacon, and British expatriates will often comment that British bacon is hard to find in the USA.
The most obvious difference is the shape and fat content of the bacon. American bacon comes in thin strips with streaks of fat running along them. British bacon is leaner, with a border of fat along one edge, and comes in a rounder shape.
The difference in shape is due to the fact that each style of bacon comes from different cuts of pork. American bacon comes from pork belly, which is a much fattier cut of meat. British bacon, on the other hand, comes from the loin which is a much leaner cut. In fact, British bacon is from the same cut as pork tenderloin. This is also where bacon gets its name; it is cut from the back of the animal (think "back-on").
British bacon is very similar to Canadian bacon, though it is fattier around the edges. American-style bacon is readily available in the UK, but it is known as "streaky bacon" due to the streaks of fat running along it. Traditional back bacon is most commonly used in sandwiches or in Full English Breakfasts, whereas streaky bacon tends to be used as trimmings on roast chicken, or wrapped around sausages as "pigs in blankets".
Speaking of sausages, this is another area where American and British foods differ.
It appears that sausages in the USA owe a lot to their European ancestry, as many are in the German bratwurst style. These are different to British sausages as they have a much higher meat content. Perhaps the most similar in flavor and texture to a traditional British sausage is the breakfast sausage.
British sausages generally have a much higher cereal content than American sausages. This is perhaps a hangover from the rationing days during the war, where butchers would bulk up their recipes with breadcrumbs, also known as rusk, and water. This higher water content is why sausages are referred to as "bangers", as in "bangers and mash". As the water in the sausage turned to steam, the sausages would often pop or bang in the frying pan.
British sausages come in a wide variety of flavors and styles, often named after the region the sausage or pig breed originated.
Cumberland sausage is unusual in that it is frequently sold by length, not by weight. It can be bought in links or as one long spiral. They are flavored with lots of black pepper, and are spicier and meatier than a lot of other varieties.
Lincolnshire sausage is a standard favorite, and is pork meat flavored with sage. It has a high bread-crumb content and has a nice herby flavor.
Pork & apple sausages are popular nationally, but particularly in the south-west region of England. They are flavored with bits of apple and cider, and even the pigs are reared in orchards where they can eat the fallen apples.
Lorne sausage is a Scottish variety that uses beef and pork meat. It is unusual in that it is sold in square slices. It can often be found as part of Scottish cooked breakfasts.
Chipolata is a French variety of sausage popular in the UK in roast dinners, particularly at Christmas. They are thin and flavored with salt, pepper, and other flavors like sage, nutmeg or pimento. Mini chipolatas are wrapped in streaky bacon, then baked, and are known as "pigs in blankets".
There you have it! A little insight into the differences between bacon and sausages in the UK and the USA. Two nations separated by a common language and pork products.