Hi, I was just wondering which plane is better/what their differences are.

The answer is simple. You can't compare these two planes.

What do you want it for? Where and how do you fly? Can you fly?

let me take a crack at it. like borderm said, apples to oranges.
the beast is 2S, biplane and has 3 axis gyro. it softens the input from the human to make it more styable. some have called it a mushy feeling. most say it handels like a much bigger plane with the AS3x gyro on it. weight 72 g

the 300 is 1s, 33 grams and has a coreless motor.pretty old school tech.

so the beast is new, faster heaiver and flys better in the wind.
the 300 is simpler, lighter and more touchy
(simple and touchy are not bad things)

my .02 from a guy who never flew them.

Both BIM and Nemoskull are right.
It depends on how you prefer to fly. if you have lots of wind outside but are a experienced 3D pilot that can fly 3D in his living room OR has access to indoor flying space, then get the extra300 otherwise get the beast 3D.

just my 0.0199999999999$

SS