There are many forums that address Ultralight backpacking. A common concept you will find is reducing your pack weight to 10 pounds to achieve the moniker "ultralight." Another is not bringing the kitchen sink. The idea is to take only what you need and will use. Many try to turn this into, "leave important stuff at home." Only idiots do either of those things. No where in UL backpacking is anyone ever told to leave a first aid kit at home, forget those prescribed pills, or not bring a map because it weighs too much. These are myths told by people to support their need to bring the Kindle, iPad, Android phone, radio, TV, and... kitchen sink. They love their sixty pound packs for a three-day hike.
Another group of enterprising individualists call themselves Bushcrafters. If they do not have it with them, they can make it or improvise. They bring tools to the outdoors. They build a place to sleep, capture/hunt/forage for food, and pride themselves on their knowledge of technique for doing it themselves.
Ultralight Backpacking is about getting from place to place. Bushcraft is about how you camp (or what you do while you are where you are). These two ideas are not at odds. In fact, these concepts combine into a modern adventurer/conservationist. Leave no trace, take only what you need, and work to improve the environment for the next adventurer/traveller. What does all this mean?
Our adventurer sets out. He (being a man I will NOT speak for women) has a ten pound backpack. His full skin out weight is twenty pounds. The load out in the backpack is very clearly what you would expect a UL backpacker carrying. The plan is to move quickly and efficiently to a camping spot two and a half days into the.... wild/desert/forest/back country. He wants to get away from people/places/things.
As a UL backpacker he eats food that he brought while he is on the way to his campground. Along the way he forages for berries, finds some edible leaves for a salad, and even identifies a wild root or two to go with dinner. He collects these and stores them, but does not eat them right away. Everything at this point is about covering ground efficiently to get to that "remote" camping spot.
Once there he no longer relies on the Gatewood cape and net tent he brought. He collects branches to put around a felled log creating a rather nice improvised shelter. He lays the branches on thick, processing them with his Grunsfors Bruks when necessary. He whips out his Cold Steel shovel and starts the process of placing a layer of dirt over the outside branches. Once a layer of dirt is down another layer of branches covers that, followed by another layer of dirt. The shelter's built. During breaks in building his shelter he set some speed hooks in a lake nearby. After a few hours he checks them and finds dinner waiting on a hook. He takes it back to his camp and cooks it with the roots, and eats the berries for a snack.
The next morning he wakes early and begins the hunt for food. He finds some edible wild mushrooms (training and a guide can confirm this) and some more greens to add to the scrambled egg powder he brought with him. It is almost an omelet when he's done cooking it. After this he goes and checks his speed hooks again and finds another fish for lunch...
After a few days out he decides it is time to break camp. He misses his wife and kids and now looks forward to missing this, his time... out. He tears down camp spreading the foliage that covered his lean-to. He breaks up the fire pit, buries ashes, and collects any trash. By the time he is done an Army sniper would not know that this was a camp site. He turns, looks behind him, and smiles, thankful that a place like this exists.
On his way back he moves quickly. His UL gear allows him to make good time, and deal with inclement weather as it happens. The packed food he brought, the white box stove, and the last of his fuel give him a satisfying cup of coffee the morning he finds his car. Recharged, rejuvenated, and excited, he drives home to see the foundation of his life, the family he loves so dearly.
This is what happens when good backpacking skills meet good camping skills. There is a destination, time, and a way to get there. To the UL'ers: You have ten pounds on your back, how many days can you stay out with it? To the Bushcrafters, if you are able to last forever out there, why kill yourself in the process?
My two cents from here: http://wn7ant.com/2013/04/18/ultralight-backpacking-and-bushcraft/