If we "turned universe upside-down" and changed all matter to anti-matter instantly
It would look very similar, but tiny differences are suspected, see e.g. this LHC experiment.

Here a list of more antimatter experiments at CERN.

See also CP violation on Wikipedia hinting towards tiny differences between matter and antimatter.

Immediate consequence: The CP violation parameter of the CKM matrix in this Wikipedia article would be different, because of different quark generation probabilities.

If you also reverse time, you'll get to the CPT theorem (Charge, Parity, Time). Matter and antimatter are thought to be symmetric in this sense.

Or to state it with simpler words: Antimatter behaves like matter travelling backward in time.