What is the main difference between active and passive voice?

In active voice, the subject performs the action; in passive voice, the subject receives the action.

Rewrite the following sentence in the passive voice: 'The dog chased the ball.'

The ball was chased by the dog.

Passive voice is used in formal writing when the action is more important than the actor, or when the actor is unknown or unimportant.

When the actor is unknown, unimportant, or when you want to avoid assigning blame.

I can rewrite sentences to change between active and passive voice.

1
The passive voice is when the object of an active sentence becomes the subject of a passive sentence.
2
We use the passive voice when the action is more important than the person doing it, in formal writing, or when we don't know who performed the action.
3
To form the passive voice, use the verb 'be' in the correct tense and the past participle of the main verb.