As you review the passage, note the tone with which Pliny addresses Trajan; note the calmness with which Pliny states that he has executed and tortured Christians; note his distaste for the idea that, among the Christians, a female slave might obtain a position of authority over free male Roman citizens; note Trajan's affirmation of what Pliny has done.
As you read Marcus Aurelius, note his tone, in contrast with the constant military conflict in which he lived most of his life, and in contrast with the orders he issued to have thousands of people, including women and children, executed for being Christians.