If I am not mistaken, JW is based on the interpretation of the Bible by a man named Russell. He decided that he didn't like the idea of 'hell' so he re-wrote the Bible, thereby creating 'his own', eliminating this concept of 'hell'. He also believed the literal meaning of the numbers mentioned in Revelation, thus teaching his followers that 'they' would be the ones alluded to in Revelations, (12,000 from each of the twelve tribes of Israel). Unfortunately for him, upon the increase of the membership of his organization 'beyond' the 144,000, he had to recant these numbers and come up with a 'new' formula with additional numbers added.
I also know from discussion with actual members, that they are not allowed to 'debate' their doctrine. They may explain their beliefs, but are NOT allowed by their 'church' to debate issues concerning 'differences' in interpretation.
They are very devoted and do NOT attend church, as traditionals practice it. They have more of an 'informational gathering', rather than a ritual infused gathering.
They do NOT believe in 'trinity'. They don't believe in hell. And they are VERY strict concerning the behavior of their members, choosing to follow a more Biblical understanding of those 'living in sin' and how they were to be treated according to their membership in the 'body'. They are also very forgiving of those that they welcome back with open arms once they have ceased their un-righteous ways.
So, in direct answer to your original question. The only real discrepancy of their belief system, as far as I can tell, would be that this Russell character created a 'cult-like' religion by 'throwing out' a number of Biblical principles for his own understanding. Other than that, these people are VERY devoted and sincere. And I only use the reference to 'cult-like' in the respect of their relationship compared to the 'traditionalist, (to them, ALL other denominations are 'cult-like'.
Hope this helps.
MEC