Bilateria are all animals having a bilaterally symmetrical animals, they have front and a back end, as well as an upside and downside.

In bilaterally symmetrical animals, nerve tissues concentrate at the anterior region, forming structures responsible for information processing.

As the term indicates, radially symmetrical animals have a globular or circular plan such as do Volvox, sea anemones, starfishes, or jellyfishes.

And we've been seeing all these radially symmetrical animals.

Wiwaxia was a bilaterally symmetrical animal.

It is also the opposite of oral which is the end containing the mouth of a radially symmetrical animal.

Consequently, scientists believe that cephalization characterized all bilaterally symmetrical animals from their origins.

The end result is a bilaterially symmetrical animal, but with its dorsoventral axis rotated a quarter of a turn.

In contrast, radially symmetrical animals like jellyfish have a topside and downside, but no front and back.