I wondered this myself and so googled it. And I found the answer PLUS to boot a Mongrel and Crossbreed Club. Fantastic. Anyhow, firstly the answer to the difference between a Mongrel and a Crossbreed. A Crossbreed dog is the result of a pure bred bitch mating with a pure bred dog of another breed. A Mongrel is the result of a Crossbreed bitch mating with a Crossbreed dog. The addy is Crossbreed and Mongrel Club.