How to get the USER avatar URL as opposed to SITE Avatar URL

Using get_avatar_url( $current_user->ID); I receive the SITE avatar URL located at gravatar.com. The same is true for get_avatar_url( get_the_author_meta ( 'ID' ));. The two URLs are different, but both are at gravatar.com.

How do I get the USER avatar URL located at mygreenboard.com? - Upon sign-up users upload their USER avatar. I need access to the USER avatar URL to copy it to another part of the mygreenboard system.

Thanks,
Rob