The four living suborders of beetles diverged from one another in the Permian and early Triassic, and are substantially different from one another. Adults differ in the structure of the prothorax, hind wing, abdomen, ovary, testes, and so on. The major differences are summarized in a table.

Polyphaga is by far the largest suborder, containing 85% of the known species, including rove beetles, scarabs, stag beetles, metallic wood-boring beetles, click beetles, fireflies, blister beetles, mealworms, ladybirds, leaf beetles, longhorn beetles, and weevils. Many are phytophagous. Adephaga includes ground beetles, tiger beetles, predacious diving beetles, and whirligig beetles; most adephagans are predacious. Myxophaga is a small suborder, containing less than 100 known species, whose members are small or minute, and associated with hygropetric habitats, drift material, or interstitial habitats among sand grains. Archostemata contains several families of beetles, most associated with wood; members of this family are somewhat similar to some of the earliest, Paleozoic beetle fossils.