Xestia caterpillars are generally stout and cryptically colored; in some species they have quite prominent dark lengthwise spots, but may e.g. be entirely green or whatever else gives best camouflage.
Xestia caterpillars are typically plump and camouflaged; some species have noticeable dark lengthwise markings, but may be entirely green or any other color that provides the best camouflage.