I've underlined "new ideas" for players to grasp here and there.
Expanded Psionics Handbook
Psion: The psion class represents a psionic manifester whose mastery of mental powers derives from study, self-reflection, and internal exploration. Each psion inclines towards specialisation in a particular discipline such as Telepathy or Psychoportation, each offering a themed set of psionic powers to supplement the powers common to every psion. Psions' powers are similar to but also different from either arcane or divine magic, deriving wholly from their mental discipline and internal wellspring of energy. Though armour does not interfere with their psionic powers, psions are generally too focused upon exploring their potential to learn more than the rudiments of mere physical combat. Psions' powers are relatively limited in their number known, but they are powered by an internal reserve of power points which can be used as the character sees fit.
Psychic Warrior: The psychic warrior class represents a skilled combatant who augments their ability on the battlefield with psionic feats and a small range of psionic powers fuelled by their own mental abilities. Psychic warriors take advantage of the fact that heavy armour does not interfere with their talents to encase themselves in the best protection they can. While their number of powers is extremely limited and their power points few, the combination of psionic ability and training in mundane combat make them formidable opponents.
Soulknife: The soulknife class represents thinking warriors who focus the power of their will into a psionic mind blade. Though their mastery of this blade leaves their mundane combat power somewhat lacking, their stealth and ability to make deadly psychic strikes helps to make up for the deficiency, as does their ability to enhance their mind blades with various supernatural special abilities. Like rogues, soulknives prefer light armours for mobility; they rely almost exclusively on their mind blades in combat.
Wilder: The wilder class represents psionic manifesters whose ability derives not from the strict discipline of the psion but from raw, powerful emotion. Knowing vastly fewer powers than psions, wilders compensate with access to wild surges of unchecked psionic energy which can empower them to produce effects more powerful than normal - at the risk, however, of injuring themselves through psychic feedback. Without the need for rigourous discipline, wilders also learn a little more in the way of mundane combat than psions.
Magic of Incarnum
Incarnate: The incarnate class represents a warrior who meldshapes the raw energy from which souls are formed - incarnum - into soulmelds which draw upon the ethical principles of the universe (Law, Chaos, Good, and Evil) to form supernatural weapons, armour, and other items to enhance their own mundane abilities and grant them supernatural powers. Incarnates are strongly wedded to the metaphysical pole they represent, and each type of incarnate has access to different soulmelds accordingly. Like all meldshapers, incarnates can bind their soulmelds to chakras within their body to amplify their effectiveness or access other powers. Incarnates can also manipulate discrete units of incarnum called essentia to improve their soulmelds and other abilities such as feats, and tend to wear armour and wield weapons befitting a skilled warrior.
Soulborn: The soulborn class represents warriors who use incarnum to enhance their natural skills, much as a psychic warrior using psionic talent does. Like incarnates, soulborns align themselves with one of the four ethical poles of the multiverse and serve as powerful combatants in the service of that principle, using essentia to improve their abilities and shaping a limited number of soulmelds as well. Soulborns can wear the heaviest armours and fight much as paladins do in the service of their causes.
Totemist: The totemist class represents warriors who shape soulmelds which mimic the supernatural abilities of the strange magical beasts of the world. Associated primarily with wild, primitive communities which revere these creatures, totemists have access to a unique totem chakra along with the regular chakras any meldshaper can bind their soulmelds to. Totemists tend to remain mobile in lighter armours and use the simpler weapons characteristic of their native cultures.
That's what they all say 
