Similarities
Aristotle, Kant, and Levinas all talk about ways that can make us have a good life. Living by their keypoints will help form a good life, as everyone will be benefiting in some way. Aristotle tells us how we can achieve this good life by being together as a community, Kant tells us we can achieve this by acting in ways that we would want others to act, and Levinas tells us how we can achieve this by helping others. All three philosophers points lead us to helping each other. Aristotle tells us to be in a community, and when we are in a community, we naturally help each other so we can ensure that our community won't fail. Kant tells us that we should act in such a way that we would want the whole world to act. Naturally we won't act badly because we don't want the entire world to go against one another. We want to live in a happy and harmonious world. Levinas tells us that when we see a person in need, we should help them. Seeing someone suffering will automatically have our senses kick in to help them, because of their pained face.
Differences
The differences between each philosopher is that they have a different way of approaching situations. Aristotle would approach a situation using reason. He would think out all the possibilities that could happen in the situation, and then consider which one would have a better outcome for both parties. Kant, in various situations, would act in such a way that he would want the whole world to act. If he thinks acting in a certain way will be bad if everyone in the world does it, then he wouldn't do it. Levinas on the other hand, would most certainly jump in and help the person when he sees them suffering. He cannot stand the pain on the Other's face, and will help him the moment he sees the Other in pain.