Generally speaking, International Law is a body of rules and guidelines that is established either through treaties or international customs. Interestingly, there is no single body of law that constitutes "International Law." Treaties are entered between various parties concerning various topics. These treaties set out rules for the States that join the treaty. These bilateral agreements are a big part of what international law is. There are also many intergovernmental and international organizations such as the United Nations (UN) who have their own body of rules. Those are also "Internationa Law" to the member states. Again, international law includes a bundle of laws and is not a system of law that stands by itself.
Human rights are moral principles that most States abide by. There are many human rights treaties between various states. These treaties set forth how each state is to treat their population, minorities, and other groups within and outside of their state lines. So, in a sense, human rights are often part of international law. However, those two things are certainly not the same thing. I hope that helps clear things up a little!