Hallucinogens are generally broken up into three classes: psychedelics, dissociatives, and deliriants. Each class has its own set of effects and mechanism of action.
Psychedelics primarily function as 5-HT receptor agonists, dissociatives are NMDA antagonists, and deliriants are muscarinic antagonists. These various actions lead to notably different experiences, though some psychedelics (e.g. DMT and 5-MeO-DMT) can provide very dissociative-like experiences.
There are some drugs which provide psychedelic and dissociative effects while functioning in a somewhat unique way, among which are ibogaine and salvinorin A. Unlike the average psychedelic or dissociative, those drugs primarily function as k-opioid agonists.