For years, Goex was the only game US maker and more or less cornered the US market. It was so much better than any imports, it had virtually no competition. When Swiss and Schutzen, etc. started importing their products into the US They lost market share to a better product.
Express is their response.
Essentially, Goex Express is an effort to cut into the premium powders marketed by Swiss. It burns cleaner because of better ingredients, and because of the better mix, it is a little hotter.