Frankly, the decisions that we make are chemical reactions. The difference is in the complexity of the decisions that we can make. At that point, though, in order to answer your question, we would need to argue about what one would consider to be a decision that’s complex enough and a decision that’s not complex enough, and that leans much more into philosophy and ethics rather than science.
I can only tell you that, from a mechanistic point of view, there’s not really much distinguishing our decision making process from, say, the decision making of a flatworm