MMA tends to be the catch all phrase for identifying
combat sports that evolved from the pure forms of combat.
Many die hard fans still use NHB/Vale Tudo/freestyle fighting/Extreme fighting or Ultimate fighting (early UFC events) to still reference the primal nature that still nurtures some of the best MMA matches "Who is the better fighter" vs. how much I'm getting paid. (Don't get me wrong...I'm not against money...it's just the fights are better when you have pride in your fighting that justifies the pay.
As far as Identifying Pancrase from pankration, shoot fighting from shoot boxing, Submission fighting from Submission grappling, Pride from the UFC and so on and so on......you simply have to follow the different companies......because there are so many variations of the rules.
Example......This past October Combatdo in Illinois was a pro fight show but did not allow knees on the ground for any reason.
The rough and Tumble challenge also in October took place in VA and was an amature card that allowed knees on the ground
Both Shows were sanctioned by the ISCF.....however, the promoter and the state commission have some say as to what is finally used in the ring.
The different types of rules change your strategy and the overall "style" of the fight.
You don't get alot guys pushing opponents into the ring
ropes on the ground in a Pride show because of the stand up rule or the restarts.....But this is a tool commonly seen in the UFC.....that's why many of the fighters are excellent at escaping up by pushing off the cage.