When two people are listed as a named insured, the second person is called the second named insured. If you’re listed as a second named insured, you can make changes to the policy and access any information a named insured would, even without approval from the other person on the policy.
Conversely, one of you could be added to the policy as an additional driver. When you’re an additional driver, you only have coverage under the policy. You can’t make any changes to the policy or access information.