Scotland Yard and the Metrolopolitan Police

What is the difference, if any, between the Metropolitan Police of Greater London and New Scotland Yard?

What actually IS New Scotland Yard? I checked around on the internet and the answers I found were not as definitive as I would like.

Thanks.

New Scotland Yard is the headquarters of the Metropolitan Police Service (actually, two different buildings have been called “New Scotland Yard”). The terms “New Scotland Yard” and “Metropolitan Police” would thus bear roughly the same relationship as “the Pentagon” and “the Department of Defense”.