I'm by no means any sort of Taylor-knowledgeable person, having never even played one until about a year ago. But…
Isn't the 810 a dreadnought? I would expect the 414 to be louder in perceived volume since it probably has stronger mids/trebles. My 414ce sounds louder than my Martin HD28…because the trebles stand out more, giving it more "edge." It's not actually louder if you measure it with a Db meter because the Martin's bass is much stronger but as far as perceived loudness to the ear, the 414 is louder, at least up to a point. If I play both guitars with maximum "energy," the dread will sound louder because the 414 hits its limit of producible volume before the dread does. I suspect something similar with what you are describing.
IOW, I believe your 810 CAN play louder than the 414 can but up to some point, the same amount of pick/finger-picking energy will result in more perceived volume from the 414 due to the greater mid/treble emphasis.