You forgot to give the definition of religion:
a. Belief in and reverence for a supernatural power or powers regarded as creator and governor of the universe.
b. A personal or institutionalized system grounded in such belief and worship.
2. The life or condition of a person in a religious order.
3. A set of beliefs, values, and practices based on the teachings of a spiritual leader.
4. A cause, principle, or activity pursued with zeal or conscientious devotion.
So if you compare the two definitions you will notice only two things that a cult has that religion doesn't; it's faddish and it's false. There are other words thrown around like unconventional but who decides what that is? In fact who decides what is false? We do. That is why every religion has been called a cult at some time or another by someone else.
The real difference? Does the religion "do harm". This is not simply requiring a set standard or tith but do you have to to "pay your way in", are people being physically abused as a standard, are they allowed to decide for themselves or does the leaders hold complete mental and emotional control.
Just about anything can be considered a cult. The real question is whether there is a victim.
PS. (Don't forget to keep in mind that cults can rise out of existing religions, hiden or otherwise, essentially seperate but preying upon them, and do.)