C. piperatus is very similar. From Baroni & Both’s description of C. piperatoides:

“Chaliciporus piperatoides is similar in appearance to C. piperatus but differs in the field by the rapid and intense change to deep blue of the pores, tubes, and the pileus and stipe context near the tubes, when these tissues are injured or exposed. Additional features which separate these two species are: 1) the pores and tube in C. piperatoides do not develop obvious reddish-vinaceous colors with ages as is seen in C. piperatus; 2) in C. piperatoides the pileus context is a pallid pinkish cinnamon to ochre-buff or orange-salmon and lacks a vinaceous-rose line under the pileus surface or just above the tubes, while C. piperatus has a pale yellow context with a distinct rose or vinaceous line below the pileus surface and above the tubes; and, 3) the spore deposit of C. piperatoides is dark smoky olive when fresh, or when viewed under a fluorescent lamp after drying, whereas the deposit of C. piperatus is a cinnamon-brown when it is fresh or is dominated by this hue when dried and then viewed under fluorescent light.”

For differentiating dried herbarium specimens they state:

“…C. piperatoides [has an] obvious fleeting amyloid reaction of the revived tube trama…. This reaction is consistent for all dried collections of C. piperatoides, while all collections of C. piperatus tested gave negative results.”