In America crumpets are called English Muffins.
In the UK there is a distinction between crumpets and English muffins as crumpets in the UK are a separate item.
Americans often use the name or term "English muffin" to describe a griddle cooked bread with a porous surface which is very similar to a crumpet.
Crumpets are a type of griddle cake that is popular in the UK and they are characterized by their porous hole filled surface.
And in the United States, the term English muffins refers to a round, flat bread with a similar porous texture that is often eaten as breakfast sandwiches or even toasted with toppings.
The similarity in appearance and the common practice of toasting and buttering both English muffins and crumpets often leads Americans to conflate the two, using "English muffin" as the general term for this type of bread.
English muffins are readily available in most American Grocery Stores, but actual crumpets can be harder to find and may be available in some specialty stores or online retailers.