downhill in it's modern day form is mostly done on dh specific courses against the clock, where the quickest time takes the win. courses mainly consist of varying features, from steep fast streights, thight twisty corners, long flat corners, berms. big jumps, roots and rock gardens, and the occaisional drop. its mianly ridden on a dh specific bike that usually has slack geo, and 8 inch of travel at both ends.
freeride in its original context was to ride with out limits or restrictions, to go where ever you wanted. now a days though it's evolved into super steep terrain, big drops and massive jumps. freeride bikes have slighly steeper geo than dh bikes and less travel. usually 7 inch. they also designed to pedal and climb better than dh bikes.
as for your bike question,,,, yes and no. is the answer.
a good rider will beable to ride any bike on any terrain, your not gonna be setting any course records on a bike like that, and it wont be very enjoyable, but it can be done...
it would be alot easier and more enjoyable with the correct bike, but somtimes you got to ride what you have, one things for sure, it will fine tune your skills and refine your technique