What distinguishes the appearance of millipedes from centipedes?

Millipedes are distinctly characterized by having two pairs of legs per body segment, leading to a generally greater number of legs compared to centipedes, which have only one pair of legs per body segment. This anatomical difference is a primary distinguishing feature between the two.

Centipedes are indeed longer and can appear larger, but the critical factor in identifying them versus millipedes lies in the leg count and distribution. Millipedes also lack the hard, rigid exoskeleton that some might associate with a "hard shell;" instead, they have a softer, segmented body. Thus, the key distinction based on appearance is indeed the greater number of legs that millipedes have compared to centipedes. This allows for easy identification and classification in the field of entomology or pest control.