I would say there is no contradiction and I agree with both. Please read on.
As many people already stated. Paul was saying the work that is required in the law should be a product of faith. Faith is good tree and good work is good fruit. If there is no good tree, the work will not be good fruit.
For the words of James, my understanding is James was saying that work and faith are not separable. Basicly, every tree bear fruits, just like every living people does something, even playing is something. Once there is faith, the tree is called good tree and the fruits will be called good fruits, even playing is good work. If the tree does not have fruits or have bad fruit, this is a sign that there is no faith.
The definition of work can be broad. Some work can be seen and some may not be seen. Only God see all the works. For example, even if we did not do anything to other people, we think of and trying to understand God's words, we are working on ourselves. This is called good works. God can see this. But people cannot see this and may say that this guy is not doing anything good. But if you think that making oneself trust in God is itself a great work, you will not say that.