Okay soooo
Let's do a quick comparison
Tumble
CD: 6 / 5 / 4 / 3 / 2
BONUS PHYSICAL DAMAGE: 30 / 40 / 50 / 60 / 70% AD
Spinning axe
CD: 12 / 11 / 10 / 9 / 8
BONUS PHYSICAL DAMAGE: 45 / 55 / 65 / 75 / 85% AD
Now comparing them like this it sort of maybe looks like Vayne's tumble is better but bear with me. Draven upon catching his axes will cause spinning axe to apply to the next auto attack with an air time of 2 seconds as you mentioned. However you forget that Draven can have TWO spinning axe's and that his base AD is much higher which means he's putting out 45 / 55 / 65 / 75 / 85% AD bonus physical damage on both his autos every 2 seconds which far outweighs Vayne's single auto every 2 seconds . Now let's remember that catching an axe also builds a stack of his passive and resets his movement speed steroid on his W.
Vayne's condemn vs Stand aside.
The functionality is different, Vayne's condemn knocks an enemy backwards and if they hit they are stunned. If Draven's stand aside hits an enemy, they are knocked sideways and slowed. I'd say stand aside is much better because it doesn't push people away and even if you wanna run away it still applies a slow while condemn stuns.
Now let's get to the ultimates, Vayne's Final hour grants her 60 AD. giving her 90 movement speed from her passive and lets tumble turn her invisible. Now this is a great ultimate but it only buffs Vayne's stats significantly.
While it's hard to compare Vayne's ult to Draven's Whirling death which deals PHYSICAL DAMAGE: 175 / 275 / 375 (+ 110% bonus AD) when used directly on the opponent, this literally chunks enemies at close range, and will cost most ADC's a huge portion of their HP.
's main strength is that 
