Remember what Jesus commanded us? "Love your neighbors as yourself." Now, we are being reminded of it. James is reminding us of this, that we should treat equally. That we should not look at a person differently just because he is inferior to you in some ways.
There are different ways in which we fail in having a favoritism. Sometimes we criticize a person just because they are less beautiful or less fortunate than we are. We oftenly judge a person by how we see them which is wrong.
To God, how we look or how much wealth we have doesn't matter. He looks at how we are inside. How much faith we have in him. How much we love him and obey his words. If we have better things than other, it doesn't matter. If we are more beautiful, it doesn't matter. If we are as poor as a lowly rat it doesn't matter. If we are as ugly as a duck, it doesn't matter. As long as we have a big faith in a big God, that is all that matters. Because if we have God in our lives, we will be complete. He will provide anything that we need. He will shower us with blessings that are beyond are imagination.