What's the difference between an arthropod vertebrate and an arthopleura? (ark reference)

One of them has bones im pretty sure

Hello, At close range even a familiar arthropod like a grasshopper may seem appallingly strange. The creature�s expressionless eyes give no indication that it can think or feel. Its colored armor plating seems more suited to a machine than to an animal. There are too many legs jointed in too many places. The abdomen pulses, the antennae twitch, and tiny oral appendages shift food to the mouth. Lean a little closer and the thing leaps, almost into one�s face, to veer off on crackling wings.