I you want to wade through technical jargon, here is what FNA says
Rhynchospora latifolia - Longer involucral bracts at least 5 mm wide at base, mostly abruptly narrowed and green at or distal to midbract; fruit widest at midbody; tubercle base lunate, decurrent; rhizomes mostly 2–4 mm thick; in acid, boggy substrates.
Rhynchospora colorata - Longer involucral bracts mostly less than 5 mm wide at base, mostly gradually narrowing, green well proximal to midbract; fruit widest at or near apex; tubercle base transverse or slightly lunate, scarcely decurrent; rhizomes mostly 2 mm or less thick; in calcareous or basic substrates.
I think the main point is R. colorata has narrower bracts and more the green portion extents higher up the bract.