As nouns the difference between dummy and mummy
is that
dummy is a silent person; a person who does not talk while
mummy is a substance used in medicine, prepared from mummified flesh.
As verbs the difference between dummy and mummy
is that
dummy is to make a mock-up or prototype version of something, without some or all off its intended functionality while
mummy is to mummify.
As a proper noun Mummy is
one's mother.