By virtue of owning a Tesla Model X and a Nissan LEAF, the Like Tesla YouTube channel was able to explore the cargo carrying capabilities of both vehicles.
The conclusion is that the Nissan LEAF has vastly more cargo space than the Tesla Model X, despite the fact that the LEAF is a smaller overall vehicle.
The problem is that the Model X's second-row seats don't fold. Those seats saps up tons of potential cargo space. Tesla says the not-yet-available 5-seat Model X will solve this non-folding-seat issue, but for now, the LEAF beats out the X in the cargo-hauling department.