Can I safely take it that in these terms the E stands for Electrode. i.e in mig meaning the torch/wire
and Tig being the tungsten. so swapping between the two for gas /gasless.
Yes, and as well as MIG wire or TIG tungstens, the E for "electrode" also applies to the welding rod in Arc welding. When Arc welding with DC, some rods have a preferred polarity.