Chionodes fumatella is generally a darker species than C. distinctella with varying degrees of blackish speckling and up to three prominent black spots on the forewing. The black spot in the centre at one-third is often present in both species but is usually more obvious and larger in C. fumatella, this feature being further accentuated by the surrounding small patches of white scales. A few scattered white scales may occur in this area in C. distinctella but they are generally less extensive.
The colour and markings can vary quite considerably within C. distinctella, the forewing colour ranging from pale to dark brown sometimes without any contrasting areas and occasionally showing strongly contrasting patches of lighter ochreous and darker brown. As can be seen with the photograph of the Invernesshire moth in the Images section this contrast does occasionally occur in C. fumatella. In the case of any doubt, they are best separated by dissection.
The uncus on the male genitalia of C. fumatella is narrower and has a short projecting thorn in the centre which can be seen under a microscope without a full dissection by brushing off the end scales from the abdomen. As C. distinctella is on the wing slightly earlier, dissection of any suspected C. fumatella in early or mid June is advisable.