Well, for a start Real Ale is not chilled. Like red wine, you don’t chill something you want to taste. Though the term “warm” which it has been called is not really true. It should be cellar temperature, so certainly not warm but sometimes that’s a struggle on a very warm day in England, so sometimes on such days a chilled beer is more in order. Also they are not gassed like lager. So flat.
In the US there tends to be four main types of craft beer: sour, IPA, Stout and Red? (This might not be completely right, I’m struggling with Red vs Golden vs maybe another I don’t drink). All tend to be chilled. Most tend to be gassed, though not sure of stout typically.
Bitter is a generic term in the UK and has no meaning really when applied to beer apart from it being an Ale, it’s like Bitter or Lager, and Bitter would be your typical pubs brewery’s standard beer, ie: London Pride in a Fullers pub.
We tend to not do sours much in the UK. That’s more a Belgian or German thing. Red beer is more on an Irish thing too, rarely see anything called that here.
However, there’s been small scale local breweries brewing something like Real ale for centuries all across England, though a lot have been bought up by the large scale breweries. They do a standard bitter, then often a special beer (stronger) and often a mild (I never was a fan but it doesn’t tend to mean weaker). Stout has been a speciality of some, but some just don’t do it. Traditionally some have done relatively strong beers, 5-6% but the brewing process wasn’t great and they often tasted quite treacly or other taste which needed acquired. Belgian beers seems to have brought better techniques and you tend to get stronger beers which taste more normal nowadays. Thus the variety is wide and differs according to regions. In the south you might get a pint which is filled to the top and have a foamy head which disappears fast to look flat, in the north you might get a creamier pint with a foam head on like lager.
Most of the time their ABV will be listed too. This seems different to the US where they don’t seem to list ABV. US craft ale also tends to be stronger. UK ale will go from 3.5% to 5.5% without comment. I’ve struggled to find less than 7% craft beer in the US.
You even get some craft lager about the UK too, but British lager in itself is pretty horrible, massively overgassed compared to anywhere else. Avoid. Not so bad when you have a craft one. Some pubs insist on having a LOT of lagers, I’ve seen some with nine different taps which seem to be largely the same tasting beer, so clearly lager drinkers care more about the labelling of themselves than the taste largely. They also tend to be “extra cold” as a marketing item. Yet, you’ll struggle to find a single one which isn’t extra cold, just adding to the ludicrousness. Guiness has went that way too, but of the friends who drink it, I regularly get the normal and the extra cold randomly and they never mention any difference.