Active puts the focus on the who or what doing something (the subject) while passive puts the focus on the who or what it’s being done to (the object).

So ‘the cat sat on the mat’ is active while ‘the mat was sat on by the cat’ is passive. Active is generally considered better because it’s more engaging and easier to read. ‘Everyone read the report’ rather than ‘the report was read by everyone’. ‘We decided to withdraw our complaint’ rather than ‘a decision has been made and the complaint has been withdrawn’. However, active isn’t always right. See tip on when it’s better to use passive.