Throat strikes of any kind, including, without limitation, grabbing the trachea. No directed throat strikes are allowed. A fighter may not gouge their fingers or thumb into their opponent’s neck or trachea in an attempt to submit their opponent. All arm chokes such as the Rear Naked, Guillotine, and bar arm are legal.
And “reality based” styles. UFC is a sport and the likes of systema and krav are more reality based. Sports styles have rules to protect the fighters, where as in reality based situations there are no rules. Meaning many of their techniques would not be permitted in a UFC bout.
The difference between UFC and Bellator is in the roster of fighters competing in each of the two promotions. Both UFC and Bellator are MMA promotions, but they have different fighters signed. UFC is the best MMA promotion, while Bellator is the second.