International laws are laws that most countries follow, most of the time. Most of the time, there aren't punishments for breaking international law, however sometimes, you may have to face sanctions/military intervention, go to international court, or face fines or punishments, depending on if you are a country, individual, or country.

Domestic laws are laws that an individual has to follow in a specific country. Breaking international law always results in a punishment, like fines, imprisonment, and in some countries, even death.

Sovereignty is the idea that a country has legal authority to their own nationality.