The Illuminates of Thanateros is essentially a practical Order, acting to organise local groups (Temples) and larger meetings, where members can take part in magical work in a group context. Plenty of other organisations exist for people who simply wish to read about magic or wish to practice on their own. The IOT strives for excellence in magical technique for those who are sufficiently self-motivated to make that effort.
The Illuminates of Thanateros represent the "organised" side of what is usually called Chaos Magic. Chaos Magic covers a variety of approaches which have in common an emphasis on the changing of belief as the core technology of magick. We take on a belief in order to achieve a particular effect on ourselves or our circumstances. The belief is only 'true' for as long as we use it; belief becomes the chief tool of magickal transformation and sorcery rather than the envelope of 'truth' inside which the magick is performed.
Chaos Magicians also emphasize 'gnosis', or the achievement of an "altered state of consciousness". Gnosis may be achieved through excitation to the point of mental saturation via e.g. dancing, drumming, sex etc., or through inhibition of the normal mental/emotional functions through prolonged meditation, stillness, breath control etc. The result in both cases is cessation of the internal monologue and a focussing of the powers of consciousness onto a single aim or symbol.
IOT Temples are autonomous, provided they follow a few basic rules, which keep the IOT's identity intact. This means that there isn't a single type of work that all Temples will engage in - each is an affinity group with its own specifications. Throughout the Pact, the variety of working paradigms and magical models used is quite extensive.