I found a question on a test asking how one could distinguish among neutrons and anti-neutrons, and I imagined at a first glance that this could be accomplished by looking at the decay products. But, since the question is not so clear, are there others, more direct ways to see the difference?
To start of with lets take a neutron. The neutron is made of three quarks. A neutron is neutral overall, however each of those quarks have a charge. This means the neutron has a magnetic moment. This is going to be reversed for antimatter. Antineutrons will have a neutral charge just like a neutron. However its quarks are going to have a charge opposite of those of the quarks of the neutron. This means its magnetic moment will be reversed. Another way could be to check out beta decay for the neutron and anti neutron. If an electron is ejected it can be said that its a neutron. However if a positron is ejected then it can be said it is the antineutron. Also the antineutron will annihilate a proton or neutron and in its place there will be pions. Positive or neutral depending on which nucleon the antineutron annihilated.