otherwise vs differently

Are these sentences correct:

[color=darkred]1-I expected him to help us, but he acted otherwise.
[color=indigo]2-I expected him to help us, but he acted differently.

[color=red]3-I expected him to help us, but he did otherwise.
[color=blue]4-I expected him to help us, but he did differently.

I find the first 3 OK.

seconded

How would “I expected him to help us, but he did different” sound?

Sounds OK to me, Ma’am. :slight_smile:

And what about this:

I expected him to help us, but he did in a different way…

Not the same meaning.

he did different = he didn’t do as we had expected.