Baronets are not peers, but males who hold a hereditary dignity (title) that passes (usually) to the eldest son. The holder of a baronetcy is addressed as “sir,” while his wife is called “lady.” A baronet’s name would be written as “Sir John Smythington-Humphries, Bt.” and addressed in person as “Sir John.” His wife would be addressed as “Lady Smythington-Humphries.”
Knights and Dames are not peers; their titles are created as a dignity within an order of chivalry (The Most Noble Order of the Garter, The Most Ancient and Most Noble Order of the Thistle, etc.), or as a knight bachelor; these dignities can be used for recipient’s lifetime only and cannot be inherited. Male holders of the title are addressed as “sir,” while the feminine equivalent of a knight is a “dame.” Until the late 20th century women could only be appointed to The Most Honourable Order of the Bath, The Most Distinguished Order of Saint Michael and Saint George, The Royal Victorian Order, and The Most Excellent Order of the British Empire. Women were prohibited from appointments to the Order of the Garter (the highest order of chivalry) and the Order of the Thistle, the second-highest chivalric order, until the 1987 reforms of Queen Elizabeth II. A chivalric knight’s name would be written as “Sir Kenneth Heffington, KT,” the last initials indicating in which order the knighthood was created (in this case, a knight of the Thistle). A bachelor knight’s name would be written as “Sir Robert Lovelace, Knight.” The wives of both kinds of knights are addressed as “lady,” followed by the surname, e.g., “Lady Lovelace.” A dame’s name is written “Dame Maggie Burnstein, GCB” (the initials stand for knight grand cross of the Order of the Bath). She would be addressed in person as “Dame Maggie.” In addition, there are classes within each chivalric order, each with a unique set of initials to be used after the person’s name. I know—it’s wicked complicated.