It's different from a zeppelin in a couple ways. First, its not totally rigid (it relies on pressure to keep it's shape), and it is negatively buoyant in the atmosphere (it relies partially on lift generated by the shape of the aircraft to stay up).
Re: negatively buoyant, that might not be true. Their FAQ states:
> Being Lighter-Than-Air, the characteristics of the Airlander bring many safety benefits. It has four engines and can fly on just one. Even if all engines fail, which is extremely unlikely, it can still float or glide under pilot control.
> As a unique part of the design, 60% of the lift
is produced aerostatically by being Lighter-Than-Air and a further 40% lift is generated aerodynamically by
having a wing-shaped hull. The engines can be rotated to provide an additional 25% of thrust up or down, to
help landing, take-off and hover.
It may technically be "lighter than air" when only considering the dry mass (I'm not sure about that), but they're definitely relying on aerodynamic lift in normal usage (so, it will glide in the same way a heavier than air plane can glide)
