Inside Mount vs Outside Mount Shades
Which mount looks better, which covers more, and which your window can actually accept.
Inside mount
Shows off trim. Requires depth. Looks architectural when the casing is worth seeing.
Outside mount
Hides unattractive frames, covers more glass, and is more forgiving if your window is out of square — which most are.
A simple rule
Pretty casing + enough depth = inside. Builder metal frames, shallow drywall returns, or a need for darkness = outside.