The Trustee can be the same and very often is the same as the 529 Plan owner.
A Trustee is not necessary for a 529 Plan but some have a Trust set up to manager the children's assets for their benefit.
The account owner
is the person who opens the 529. As the account owner, this person
manages the college saving plan: selecting or changing the beneficiary,
selecting the investment options, making withdrawals, terminating the
account, and receiving withdrawals if no other person is designated. The
account owner also makes contributions to the account, but others can
help, too.