in addition of what Johnny said, here's the explanation to 2T (2-stroke/2cycle oil) types and how to pick the correct grade for the function.
Air-cooled 2-cycle engines such as go-cart, chainsaw,weedwacker, genset, etc. runs hot and would require low-ash 2-cycle oil to go with it. Don't worry about the term "ash" for it's the byproducts of detergency (metallic based) that helps in keeping the internal engine clean and with proper blend (1/2 syn is a good beginning, full-syn is the best) with JASO FC or better (currently, the best is JASO FD) and/or in combination with ISO-l-EGD will give you best possible engine protection (to keep the piston skirt from scuffing, engine seizing up during extreme heat, reduce any possibility of ring sticking, gumming up/carboning up of the exhaust port or power valve and/or combustion chamber,etc.) In other words: JASO FD oil with additional ISO-l-EGD rating would keep your engine running at it's best for the longest possible life attainable. If you figure that JASO FC rated oil is very low smoke, try FD rated and you'll be genuinely surprised how little/no smoke it burns and it's so clean, there's no gum or soot left behind at all...
API TC is the most basic (or bare-minimum) 2T air-cooled oil specification. Don't buy any oil that fails to meet at least JASO FC (these days, you may still come across some #@$%! FB or FA rated oil in some poor countries such as Thailand where "tuk-tuk" runs on them and smoking up the city)
NMMA approved motor oils are meant to be used in water-cooled 2-cycle engine that has a lower engine head temperature. oils destined for use in these engine types sometimes come with no-ash formula which is not something that we would like to see in an ordinary air-cooled 2T engine (remember: we need those detergency formed low ash oil to keep the engine clean. Also: API TCW/NMMA rated 2T oils comes with different formulation that would not only runs like sheet in ordinary air-cooled engine, but also gums up the engine, causes ring sticking, etc.