Yes there is a difference between hydraulic and mechanical brakes, at least twice as much power, better lever adjustments with hydraulic brakes. The only bad ones are old SRAMs and they were redesigned for 2015. I learned the difference on how fast discs will stop you when I encountered my first rattlesnake! and flew over it. The bike stopped before the snake.
As a heavy guy I say quality rim brakes over lower level mechanical discs, and Hydraulics over everything period. A big plus for discs is that you can taco your wheel and stomp it back enough to get home and your brakes will be just fine, unlike rim brakes.
I just installed shimano xtr hydros and my bike stops faster than any i have ever ridden with outstanding brake modulation as well.