What are the non-physical differences between humans and animals?

What morally relevant differences are there, if any, between developmentally challenged humans and non-human animals?

• By morally relevant differences I mean differences between the entities which justify according greater moral value to one than the other. For example, we tend to think humans are of greater moral value than rocks. There are many difference between humans and rocks which might explain this. One difference which seems morally relevant is that humans are sentient. One difference which seems irrelevant is that rocks are more dense (i.e. density of an entity is morally irrelevant). By developmentally challenged humans I mean humans who lack "normal" cognitive sophistication found in most adult humans (i.e. humans who are as cognitively sophisticated as chickens, for example). By non-human animals I am referring to non-human sentient entities including: chickens, pigs, cows, mice, dolphins, etc.

• Answer:

  Humans can define their own reality through an infinitely expandable vocabulary capable of expressing infinitely expandable concepts.  Animals cannot do that with their limited vernacular.  One nation defines a reality where whale hunting is good.  Another defines a reality where whale hunting is bad.  Animals cannot do that.  And upon our ability to define reality, morality is born.