There is a big difference between MIG and TIG welding, in both the process, and the skill level required of the weldor. They really are two different processes altogether, and the MIG is the much easier of the two. There is much to read on the web, including some great information at the Miller and Lincoln websites. They can give you a pretty great overview of TIG welding. But, as with many skills, it takes hands-on practice as well as study, to be successful. If your fiance has ever welded with a gas torch, he might already have the skills he needs. Unlike a MIG welder, a TIG does not feed an electrified filler wire for you. You are in control of a separate heat source (the torch) that you must manipulate in order to melt the base metal together, while adding the filler by hand to the molten puddle you're creating. It's the same way a gas torch works, just with electricity, rather than gas, as the heat source. The tricky part comes in learning how hot to make the puddle, how much heat to apply (with a foot or hand controller), and how to coordinate the filler at the same time. Quite often, TIG welding involves metals like aluminum or stainless, which have their own quirks that need to be considered. It's by no means impossible to learn all of this...and it can be a very valuable skill to have, often paying higher than MIG welding jobs. If your fiance shows this prospective employer that he is a professional who takes pride in his work, has studied the subject, and is willing to learn, he may get his foot in the door and start down a new path on his welding career. I wish him the best. Study all you can, and if you know a buddy who is good with the Oxy-Acetylene torch, go visit him right away for some practice! Best of Luck!