Forskellen på dyr og planter er at dyr har sanser, et redskab der bruges til at få input fra omgivelserne og derved reagere ud fra det. Dog vil dyr der har et defekt sanseapparat ikke blive betegnet som planter.
Der ud over der der forskel i strukturen på cellevægen ved dyr og planter.
Tree of Life web project: Discussion of Phylogenetic Relationships Citat: "...Due to new evidence from developmental biology and molecular phylogenetics, ideas about bilaterian relationships have undergone a major paradigm shift within the last decade. The new hypotheses shown in the tree above are now widely accepted, but there are also many sceptics who emphasize the pitfalls and inconsistencies associated with the new data. One of the most prominent alternative views based on morphological evidence is championed by Nielsen (2001)..."