Is the English imperative ever different from the infinitive

Solution 1:

In a comment, John Lawler wrote:

Yes. The imperative construction is formed from the infinitive verb form in all cases. Except for the auxiliary be, the infinitive verb form is the same as the present tense form in all but the third person singular; be is the only English verb with a special infinitive form.

Solution 2:

We always use the infinitive without to to form the imperative.

However, the structure of the imperative sentence in the passive voice is different from the one in the active voice. Changing the voice, we change the form of the verb.

Compare:

Active voice: Do it now.

Passive voice: Let it be done now.