What three things differ greatly from one welding process to another?

Three key differences among welding processes include the type of energy source used, the materials and filler metals employed, and the welding environment or conditions. For instance, processes like MIG welding use a continuous wire feed and gas shielding, while TIG welding relies on a tungsten electrode and requires more precise control. Additionally, some methods are better suited for specific materials, such as aluminum or stainless steel, while others may be more versatile. Lastly, the level of skill and safety considerations also vary significantly between different welding techniques.