These two species are often hard to separate because of the confusing range for the macrocharacters which overlap. C. perennis seems to be the more cinnamon of the two, but not always! The width of the spores is a good microcharacter.

Coltricia cinnamomea
Cap 1-5 cm, vivid reddish brown (rusty aging amber) to dark brown aging wood brown; Zoned but somewhat blurred by radially fibrillose matted fibers, edges of zones often diffuse; Center flat to depressed, margin paper thin and hairy (ragged looking).
Pores reddish brown aging tan, not decurrent on stalk.
Spores 6.5-7.5 × 4.5-6.5 um (Hansen & Knudsen, 1997)
Photo: MycoBlitz
Photo: http://MykoWeb

Coltricia perennis
Cap 2-13 cm, whitish tan, soft orangish brown, yellow brown (golden cinnamon) to dark brown aging grayish; Distinctly zoned with sharp edges; Radially fibrillose or appressed velutinate surface; Center flat to depressed, margin thin and rounded.
Pores grayish brown aging tan, normally decurrent on stalk.
Spores 6.5-9 × 3.5-5 um (Hansen & Knudsen, 1997)
Photo: http://MykoWeb

References:

Bernicchia, Annarosa. 2005. Polyporaceae s.l. Fungi Europaei Vol. 10. Edizioni Candusso, Alassio, Italy. 806p.
Bessette, A., A. Bessette and D. Fischer 1997. Mushrooms of Northeastern North America. Syracuse University Press, Syracuse, NY. 582p.
Gilbertson, R. L. and L. Ryvarden. 1986. North American Polypores Vol. 1. Fungiflora, Oslo, Norway. 433p.
Hanson, Lise and Henning Knudsen. 1997. Nordic Macromycetes Vol. 3: Heterobasidioid, Aphyllophoroid and Gastromycetoid Basidiomycetes. Nordsvamp Pub., Copenhagen, Denmark. 444p.
Overholts, L. O. 1967. The Polyporaceae of the United States, Alaska and Canada. Univ. of Michigan Press, Ann Arbor, Michigan. 466p.