No ever said hammock camping is lighter than tenting but it can be depending on the tent, sleeping bag, and pad you are using.
Tent Fly = Hammock tarp
Tent = Hammock
Sleeping bag = Top Quilt (TQ)
Pad = Under Quilt (UQ) or pad
What many of us hangers gain is an excellent nights sleep compared to a terrible nights sleeping on th ground. Also hammock hangers usually have more options as to where to set up there hammocks as we do not need level ground free of rocks and tree roots.
Go to a group hammock hang where you can check out a variety of different setups.
I have a variety of TQs and UQs so depending on the weather my Hammock, tarp, TQ, UQ, Stakes, tie out lines and a pillow weights in at under 6 lbs for summer time. Changing to my winter TQ and UQ may add a couple of pounds.