What is the term used to describe English words that sound the same but are spelt differently?
It is a type of homophone – words that sound alike but have different meanings. If a homophone sounds alike, but is spelled the same, it is a homograph. If it sounds alike but is spelled differently, it is a heterograph. To, too, and two are examples of homophones that are heterographs. Bark (of a tree) and bark (of a dog) are examples of homophones that are homographs.