Passive voice is used in a clause whose subject is unknown , unimportant , common , or obvious. In passive voice object will replace the subject and subject will be removed.
Active voice is used in a clause or a sentence whose subject expresses the main verb's agent. The subject and the object of the sentence come in it's order in active voice .
Example : People speak spanish in spain => active voice , people is the subject.
Spanish is spoken in spain => passive voice , ( the subject is obvious to us )
The pic above :
number 1 : As you see in that sentence the subject of the sentence (we) has came directly in the sentence so this is an action voice .
number 2 : But in this one when you read the sentence , you immediately ask yourself "who ?" so the subject is unknown therefore this is an passive voice .
I hope it helped.
