Are there different grades or styles of bacon?
In the UK there are two main cuts of bacon.

There's "streaky bacon", which is cut from the pork belly.   This is mostly what you get in the US.

There's also "back bacon" which is cut from the pork loin.  This is generally more popular and is very much leaner than streaky bacon.  In the US you call it "Canadian bacon".

You can also get "middle bacon" which is cut from both, i.e. a contiguous cut from belly to loin - a piece of streaky bacon and back bacon combined.