Here are some differences between Shark Navigator Lift Away and Powered Lift Away.

1, The Shark Navigator Powered Lift Away, such as the NV581, NV581Q, and NV583, allows you to use the powered nozzle in both upright and lift away mode. So you can clean under furniture with the low profile powered nozzle without switching to other tools.
Whereas the Navigator Lift Away models, such as the NV352 and NV356E, only allows you to use the powered head when in upright mode. You have to use the other attachments when in lift away mode.

2, The Powered Lift Away has the floor selector on the handle whereas the Lift Away has the floor switch on the top of the canister.

3, The Powered Lift Away has LED lights on the floor nozzle whereas the Lift Away does not have headlight.