With most welders you can dial down the heat and do very light work, but if welder does not produce enough heat (amperage) being to small you can turn it up to the max and it still may not be enough so you may need a bigger welder (more amperage capable)......
Understand voltage and amperage in any welding is a matter of just producing enough heat (at arc/puddle) to create fusion bond...
SMAW is a term Stick Metal Arc Welding it's just a technique using a stick electrode usually flux coated to add filler material into fusion bond created by arc.
GMAW in MIG welding is Gas Metal Arc Welding, wire machine feeds a solid wire "electrode" from reel in machine and control flow of shield gas to around arc/puddle to protect it from oxygen till it solidifies...
FCAW in MIG welding is Flux Core Arc Welding, wire machine feeds a tubular wire "electrode" ( the encloses a flux core) from reel i machine and and "flux" creates a shield of gas around arc/puddle to protect it from oxygen till it solidifies...
TIG is Tungsten Inert Gas welding and is sort of above what you need to know at beginners level, but its using a tungsten rod and a shield gas (usually argon) to create a arc/puddle at the joining of two pieces of material to be bonded and unlike SMAW or MIG the welder has to manually feed filler rod into fusion bond.... Very similar concept to oxy/acet welding but using a electrical arc instead of a fuel (gas) and oxygen...
Might want to invest in something like this to help you understand what it's all about, mugh get it online or drop buy local public library to see if the have some books on welding...
Dale