There are quite a few different options and routes you could take... I'm pretty sure the CBD vs THC has less to do with methods of extractions and more to do with the strain and methods used for growing, but primarily the strain. Quite a few new high CBD strains are popping up in the medical dispenseries in California for treatment of schizophrenia and similar ailments. As far as I know, the majority of material that is of medicinal value is in the trichomes, or crystals of the plant. This would include THC and CBDs. So if you want a high CBD concentrate, you would need to start with a plant that is high in CBDs and low in THC. From there the extraction process would be the same, depending on which route you would like to go. When the trichomes are on the plant they are not bioavaible due to an extra carbon being attached(WARNING: laymans chemistry). The reason you can smoke the plant matter and get high is because burning is one way to remove the extra carbon, making it able to enter your blood/brain barrier and attach to your receptors.
Another way of removing the extra carbon is by using heat and an oil. This is what is called canna butter, or edibles. Without getting into the details, to make cannabutter you would start by grinding up your high CBD marijuana product(trim,buds,shake), then putting it in a specified amount of oil based on the amount of product used. If you stay within a certain temperature window you can break off the extra carbon leaving the bioavailable trichome in the oil/butter, or making the weed "active". You then strain out the plant matter and discard, and can use the butter/oil for cooking or eat it plain. You can use bubble hash or BHO to make a stronger concentrate of canna butter. Its called cannabutter but any edible oil such as coconut oil will work. The difference between the oil in cannabutter and the oil in BHO/wax is that cannabutter uses an edible oil to soak up the activated trichomes, BHO/wax uses a generally poisonous solvent like Butane or CO2 to break off the trichomes then is boiled away to leave you with a "trichome oil", or a very high concentrate of cannabinoids and resins while very little plant matter and no solvent if done properly.
You can do something similar with a high proof alcohol made for human consumption such as ever clear by soaking or bathing the weed in the alcohol for a specified amount of time, then either drinking it from there or ways to further refine to remove some/all of the alcohol/ Removing the alcohol would make it into a wax/hash type concentrate.
Hash is a generalized word used for marijuana concentrates, specifically the smokeable form. Among smokeable concentrates you have largely two categories: bubble hash and wax. Bubble hash is a concentrate made from grinding up either buds, shake, or trim, putting it in an ice water bath and causing agitation to the point that the trichomes freeze and break off the plant matter, then using a series of micron filters, filtering out the plant matter and then different grades of bubble hash. This method uses to solvents, only ice, water, and filters.
Wax is almost a world of its own. There are so many different forms and methods for producing wax, or BHO(butane hash oil) it is really a developing science yet to be truly perfected imo. BHO has been around for decades, but people are finding many new ways and products to further/better refine the product. A quick rundown on the few different methods I know of real quick tho... First off lets deal with the semantics. There are many names that BHO will go by, and many different forms it will come in. BHO, hash oil, honey, honey oil, oil, dabs, wax, honey comb, shatter, clear, earwax, and probably a lot more are some of the different names. Its all BHO because the concentrate is formed by blasting butane through a sealed tube with ground up weed inside of it, butane coming through one side, a filter with the butane slowly dripping out on the bottom side of the tube. You cannot consume this yet, it is the trichomes+butane still. What and how you go about extracting the butane will determine the end product, but all methods involve using indirect heat with NO FLAME to boil off the gas, leaving just the concentrate. To truly get a good extraction it must be taken a step further and either put in a vacuum and heat applied to it, or using grain alcohol and then applying heat to it. Either way, it must be done outdoors in a well ventilated area. You probably heard of people blowing themselves up by now. They didn't have a well ventilated area and had open flame. Not a good combo.
There are so many different variable when it comes to BHO, if you are going to go down that route be advised that it takes a lot of practice(and thus a fair chunk of change) to really perfect it and get a clean end product. BE WARNED: there are a LOT, A LOT of people out there who post videos and offer advice on how to make the "cleanest" product who do not make a clean product. Smoking dirty BHO is not a good thing. Even if you vacuum purge or alcohol purge(winterization) it is possible to still have butane in your end product, although it may be insignificant it should be considered if being used for a medicinal purpose. The only way to know for sure is to have a lab test it, which may or may not be available in your are
