A <ul> is a list of things whose order makes no difference to its meaning. Rearranging a <ul> would change the presentation, not the information. Rearranging an <ol> would change both.

  <ul> Players
    <li> Alice
    <li> Bob
    <li> Carol
  </ul>

  <ol> Leaderboard
    <li> Bob
    <li> Alice
    <li> Carol
  </ol>