The subject makes perfect sense and concerns us all.
In spite the slippery diversity of the complex causes of varying dream types, we have some data deriving from science, experience, intuition, history, tradition and shamanism.
I will try to recall some basic parameters:
1. Body related: food, drink, hunger, need for urination, fatigue, etc. they all may intervene in the dreaming process.
2. Environment: heat, cold, familiarity or strangeness of sleeping area, external noise, psychic burdens (or sanctity) related to specific space, have definite effects on the dreaming contents.
3. The specific psychic state or attitude in which one goes to bed.
4. Preparation, or intention, prayer, or psychic plea of a dreamer in need.
5. Memories: Here we have a great variety coming from accumulated personal recollections that are interwinning in ever changing combinations, that look a lot like an unending defragment of our subconscious storage. A most remarkable chapter in our every night activity.
6. Archetypes: They speak with a symbolic language feeding us with important data that guide and enlighten us. Fortunately, or unfortunately, only the dreamer may undecipher responsibly their message, depending on his intuition. Doctor Carl Young extensively used them in psychotherapy -far beyond Freud's sexual attributes-.
7. Problem solving. Be it mathematics, or social, or survival, or anything your heart desires you are supplied with an adequate answer. A vast array of historical dreams have been recorded proving this unique dream power in problem solving.
8. Healing. Therapeutic dreams in various forms of application.
9. Mystic dreams. Where as an initiate you are offered guidance or ordered to complete a divine mission.
10. Shamanic dreams. Where a shaman uses shamanic dream-trance to guide you.
11. Precognitive. They describe in advance the exact contents of a future event.
12. Prophetic. We all know about them from religions.
13. Enkoimisis. A remarkable healing preparation dream used by ancient Greek doctors who put their patients to sleep into Aesculapius temple before treatment. After next day awakening patients provided their dream description and healers decided the proper treatment based on the dream provided by the patient.
14. Entheogenic dreams. Well known in Siberia and South America. Now also available in our societies but largely prohibited by law and called unfairly "Hallucinative". Medical doctors that used psychedelic drugs in research for 15 years before prohibition, have reported their immence contribution in healing psycho related cases.
In spite the long list i doubt if I know them all.
Worth mentioning that the above types occur mostly mixed because of the variety of factors involved.
And the best part is that we did not mention the Lucid Dreaming that when involved with the said types changes everything according to the evolutionary attainment of the dreamer...