During Jane Austen's time, English society revolved around a social hierarchy that managed much of what one did or could say. This then reflected much on your particular position within the British Empire (and other similar establishments elsewhere). One's rank (title, or lack thereof) greatly determined one's social class and inherent benefits of "the good life". Royalty was always held in the highest position by default though, even among royals, there proved a pecking order of sorts, an order that - in some form - still exists even today. Below is a basic listing of various ranks and their respective orders which prove useful in piecing together a perspective from which Jane Austen approached her very works.
Royalty (called “your Majesty” or "your Highness"):
Nobility (called “Lord/Lady”):
Commoners (called "Sir/Lady" or "Mister/Mrs."):
Landed gentry (land-owners)
*To distinguish between a noble Lady (i.e. daughter of an earl) and a non-noble Lady (i.e. wife of a knight), the first name of a noblewoman was used with her title. For example: Lady Catherine de Bourgh is of noble lineage while Lady Lucas is not.
Other Gentlemen (called "Mister" or rank title "Captain, Colonel, etc..."):
Navy and Army officers