Alea Iacta Est

A substantial guide to addressing nobles appears elsewhere, and includes much of the information you might need for dealing with them. Here are a few slightly more game-oriented comments.

Types of Title
The Unlanded ranks are the lowest kind.
Typically every adult male who is not commissioned into a guild or ordained into the Church will be knighted, along with some of the women (depending on the House). Knighthood is not hereditary, nor is it tied to a particular place or court.
A baronetcy is normally a hereditary knighthood. Particularly successful and valuable knights are made Baronet, although obviously most modern Baronets have inherited the title. A woman inherits a baronetcy (or is created the rank) is termed Baronetess.

Landed noble titles imply dominion over - and responsibility for - a noble fief. The landed noble titles are those from Baron upward, or arguably from Baron to Duke inclusive.
A landed noble in Fading Suns is usually ruling land owned by a superior (ultimately the head of the House in most cases), although in some cases a noble may own his own land. Generally the difference is small; both swear allegiance to their immediate superior and are liable for taxes and/or troops, and both could have their land taken easily enough if the might of their House turns on them.
If your father is a landed noble and you are his eldest son, then becoming one in your own right is just a matter of time. Otherwise, gaining a fief is extremely difficult, since the land has to come from somewhere. When a nobleman dies without heirs his title becomes extinct, and could be created again by the owner of the land. Acts of treason or gross negligence sometimes give the House enough reason to take titles from their current owners, but generally punishing existing nobles in this way only damages the House. The only other way for a House to make new fiefs is to gain land, but with the internal borders of the Known Worlds more or less fixed, the only real avenues for expansion are with House Hawkwood into Vuldrok space or the Hazat into the Kurga Caliphate.

Courtesy titles are granted to the heirs of high-ranking noble. For example, if a Duke also holds a Countship and a Viscountcy, then he might hold the Dukedom in his own right and allow his eldest son to be styled Count as a courtesy. Often these arrangements are written into the Letters Patent when the titles are created.
Note that it is possible to hold more than one title for the same fief; perhaps be Marquess and Earl. In most Houses there cannot be more than one nobleman per fief, so these titles must remain held by the same person and neither can be a courtesy title.
There is one notable exception to that rule: if a House has lost the land for a fief but has not dissolved the title, it may be that another now has their own title created on the same fief...

Victory titles are sometimes granted to leaders of successful military campaigns. They are styled as landed titles but differ from true titles in that the creating authority doesn't have the power to grant the fief descibed, so the title is entirely honorary. For this reason, the Houses in Fading Suns tend to steer clear of such titles.
More or less opposite are those titles pertaining to fiefs no longer controlled by the granting House. Originally a title would be dissolved if the corresponding land was lost, but recently - especially during the Emperor Wars - it has been common to leave the title in place, assuming the land will eventually be recovered...

Table of Titles
Here is the expanded table of noble ranks.

Notes and Variations
Since the table in the rulebook does not contain Viscount, everything above that has increased in points value. Prince obviously is off the top of the table in the rules; some Houses don't even use it.