The primary difference between K-type files and K-type reamers lies in the number and spacing of cutting spirals or flutes per unit length. K-files have more closely spaced, twisted spirals that provide a scraping action used primarily for enlarging and shaping the canal walls. In contrast, K-reamers have fewer but wider spaced spirals, allowing for a more efficient cutting and widening of the canal with a reaming motion. This structural difference directly affects their cutting efficiency and clinical use during endodontic instrumentation.

Reference: Cohen's Pathways of the Pulp, 12th Edition.