crumpets are different from muffins.
"A muffin (or, in North America, English muffin) is a small, round, flat type of yeast-leavened bread almost always dusted with cornmeal, which is commonly served split horizontally, toasted, and buttered"
https://1.bp.blogspot.com/_lXd-n5Kab50/SookF5CNTeI/AAAAAAAAA0U/McdSy8ZTKLc/s400/Poll+-+2009-08-18+-+Muffin+-+English.jpg
"A crumpet /ˈkrʌmpɨt/ ( listen) is a sweet and savoury bread snack made from flour and yeast."
https://upload.wikimedia.org/wikipedia/commons/3/38/Buttered_crumpet2.jpg
an english muffin is what they cut in half an use in mcdonalds for mcmuffins. crumpets you just toast or grill, they are not cut in half or anything.