Hi David,
let me first say that no, questions never offend any muslim.
a muslim would even be happy if a non-muslim asked him or her about anything related to his or her religion.
I would even go as far as thanking you for your polite question seeking knowledge about islam and the muslims.
let me start by saying this.
Allah tells us in the Koran that the jinn DO in fact exist... they are not human beings, they are different.....
demons ? yes, some of them are demons, but those are the bad ones... Shaitan in muslim belief is the Father and Chief of all Jinn, demons AND good jinn.
you can infer from that the muslim belief is that Jinn are two groups, demons, and muslims.
and there is no doubt about this belief in islam, among scholars or just any average muslim, for one reason : it is clearly mentioned in the Koran.
When something is clear in the Koran, there is no question and no debate about it among muslims. Examples of that are like that Alcohol is NOT allowed, Porc meat is not allowed, Sex outside marriage, Homosexuality, Bad Treatment to your mum and dad, and the like...
Questions that are not clearly mentioned in Koran , and about which there are some differences among different schools in islam are like :
Purity, the rituals and how to do that.
Prayers, what must be said, and what is recommended.
Commerce, a lot of details.
of course, there are some principles about those that all muslims agree on, once more, for it is clearly mentioned in the Koran or in what the prophet said.
but those two, the koran and the sayings of the prophet, do not answer ALL questions at all times ..... and THUS, the need for Scholars of islam that we call Mujtahids, those who seek in those texts, the Koran and the sayings of the prophet, for a question or an issue that is similar to what they are being asked about, and give the judgment in islam by basing their reasoning on this analogy and similarity between the two cases.
so back to your original question, NO , common muslim belief about the jinn is unified... for this is in the Koran. Yet, you might find some differences about Jinn among some schools concerning the details..... not the main issues.
what are those main issues mentioned in the Koran about the jinn :
Some of them have special powers (can fly or move very fast from one place to another)
some of them are believers and they are even Great muslims.
some of them are not muslims.
some of them help us
some of them hurt us
and the like.
I hope I answered your question enough.
To be honest with you, I would love to tell you much more, only if I had the time for that.
but I am confident many others of our friends here on TAI would be happy to answer you with some more details.
take care.
sunshine.