Chile with an “e” at the end is the correct spelling of the spicy red or green pepper in Spanish speaking countries and parts of the US. The plural is “chiles”. However in most parts of the US the term “chili” like in “Chili con Carne” is used for the peppers and the pepper powder. That’s confusing!
“Chile Powder” is the condiment containing only chiles, whereas “Chili Powder” is a spice mix. McCormick’s chili powder contains “chili peppers (the incorrect spelling), spices (no further details), salt, and silicon dioxide”. What I normally use are fresh or dried chiles, they give the best aroma. I might use chile powder once in a while, like the “Ancho Chile Pepper” powder from McCormick for Mexican or Tex-Mex seasonings. The ancho chile powder contains only dried ancho chile peppers and, like most condiment powders, silicon dioxide. This is an anticaking agent deemed harmless by the FDA, albeit the EFSA (European Food Safety Agency) recently raised concerns due to the use of nanoparticles.
The third version, “chilli,” is the spelling used in Britain, Australia, New Zealand and some other countries”.
In many countries the term “Red Pepper Flakes” is used for dried, crushed chile.