A minor difference between the US and the UK is advertising the post.
Growing up, I remember my parents reading the ads that came with the Sunday paper. We don’t actually subscribe to any papers, but despite this, every Wednesday or so, we get a bunch of ads in our mailbox. USPS is happy to pass on ads for a fee. The vast majority of these are for grocery stores.
Much less of this happened to us in Britain, so this was new to Chris.
Here’s the blog post of Chris’s reaction to American postal ads: