What is the difference between a long Birth Certificate and a short Birth Certificate?

A long (or full)  Birth Certificate contains details of both parents place of birth, whereas as a short Birth Certificate does not. This is important because under the 1981 British Nationality Act, anyone born in the UK after the 1st January 1983 is not automatically a British citizen by virtue of place of birth - This must be conferred be one or both parents. Therefore, a long Birth Certificate showing that one or both parents was born in the UK is accepted by the Home Office as a proof of British citizenship, whereas a short Birth Certificate is not.