Direct Answer
No, Sam Vanderpump and Lisa Vanderpump are not related. They share the same surname because they were both married to men named "Vanderpump". Lisa Vanderpump is a British restaurateur and reality television personality married to real estate developer Ken Vanderpump. Sam Vanderpump is an American television personality and restaurateur married to British reality star Tom Sandford, who formerly used the surname Vanderpump in some business contexts. There is no familial connection between them.