Is "We are all the same; We are all different" an antimetabole?
It's not an antimetabole. I think it's more of an anaphora.
Antimetabole is when a phrase in the first part of a sentence is turned around in the second part. For instance, I can say:
If you love to live, you live to love.
In our question, we don't have an antimetabole structure. So what do we have? I think it's more like an anaphora, which is the repetition of the first part of a phrase to achieve an artistic effect. For instance, I can say:
I struggle to wake up in the morning and I struggle to get around for the day. I struggle to get to work on time and I struggle to get through the day. Thank goodness I have no trouble sleeping.