To anwer your first question framers traditionally typically only would build things out of lumber, over time buildings codes have become more stringent so as a result framers have begun to use other materials other than lumber. As An example This job in particular one of the structures we are building will have steel I-beams holding up parts of the building.
For your second question It depends, I've done some basic plumbing and electrical work and I may do some on this job. Specialized tradesmen Plumbers, electricians, HVAC, framers, Masonry and bricklayers, ironworkers,etc, often time can/do cross into other disciplines for basic things. There are somethings that unless you have the training and/or the special tools, like HVAC you simple can't do.
There are separate names for subdisplines of carpentry and construction. I'ved copied and pasted a section of a Wikipedia article on carpentry. I think this explains it better when it comes to the different subdisplines of carpentry and their specific names.
"Types and occupations cabinetry, furniture making, fine woodworking, model building, instrument making, parquetry, joinery, or other carpentry where exact joints and minimal margins of error are important. Some large-scale construction may be of an exactitude and artistry that it is classed as finish carpentry.
A carpenter and joiner is one who has a much broader skill ranging from joinery, finishing carpentry, building construction and form work.
A trim carpenter specializes in molding and trim, such as door and window casings, mantels, baseboards, and other types of ornamental work. Cabinet installers may also be referred to as trim carpenters.
A cabinetmaker is a carpenter who does fine and detailed work specializing in the making of cabinets made from wood, wardrobes, dressers, storage chests, and other furniture designed for storage.
A ship's carpenter specializes in shipbuilding, maintenance, repair techniques and carpentry specific to nautical needs in addition to many other on-board tasks; usually the term refers to a carpenter who has a post on a specific ship. Steel warships as well as wooden ones need ship's carpenters, especially for making emergency repairs in the case of battle or storm damage.
A shipwright builds wooden ships on land.
A cooper is someone who makes barrels: wooden staved vessels of a conical form, of greater length than breadth.
A scenic carpenter builds and dismantles temporary scenery and sets in film-making, television, and the theater.
A framer is a carpenter who builds the skeletal structure or wooden framework of buildings, most often in the platform framing method. Historically, balloon framing was used until the 1950s when fire safety concerns made platform framing inherently better. A carpenter who specializes in building with timbers rather than studs is known as a timber framer and does traditional timber framing with wooden joints, including mortise-and-tenon joinery, post and beam work with metal connectors, or pole building framing.
A luthier is someone who makes or repairs stringed instruments. The word luthier comes from the French word for lute, "luth".
A log builder builds structures of stacked, horizontal logs including houses, barns, churches, fortifications, and more.
A formwork carpenter creates the shuttering and falsework used in concrete construction.
In Japanese carpentry, daiku is the simple term for carpenter, a miya-daiku (temple carpenter) performs the work of both architect and builder of shrines and temples, and a sukiya-daiku works on teahouse construction and houses. Sashimono-shi build furniture and tateguya do interior finishing work.[20]
A restoration carpenter is a carpenter who works in historic building restoration, someone who restores a structure to a former state.
A conservation carpenter works in architectural conservation, known in the U.S. as a "preservation carpenter" who works in historic preservation, someone who keeps structures from changing.
Green carpentry is the specialization in the use of environmentally friendly,[21] energy-efficient[22] and sustainable[23] sources of building materials for use in construction projects. They also practice building methods that require using less material and material that has the same structural soundness.[24]"
Framing differs from other types of building. When it comes to the material,techniques,tools, things like that.
Did I anwer all your questions? Does all of that make any sense? I'm happy to anwer anymore questions you may have.