A treaty is "An international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation." Vienna Convention on the Law of Treaties, Article 2. "Whatever its particular designation" includes conventions, agreements, covenants, charters, protocols, pacts, accords, constitutions of international organizations, and U.S. Executive Agreements.
Bilateral treaties have two parties. They usually enter into force on a date set out in the treaty. Find them in treaty publications of those two countries, or in the UN Treaties Collection.
Multilateral treaties have several or many parties. They usually enter into force when ratified by the minimum number of parties specified in the treaty. They are usually sponsored by and deposited with the secretariat of an international organization.
Treaties may be self-executing or non-self-executing. Self-Executing treaties and agreements have the force of law without needing subsequent congressional action. Non-Self-Executing Agreements require implementing legislation. Agreements may be found to be non-self-executing because of terms in the agreement itself, because of Senate reservations, declarations, or understandings, or because of constitutional requirements. Find U.S. implementing legislation by searching the treaty in U.S. statutes, or for other countries in State Party Reports.
For U.S. Treaties:
Executive Agreements are International agreements entered into by the President which don't require consent by the Senate, and are therefore used more frequently than treaties.
Congressional-Executive Agreements are based on laws authorizing such agreements, or are submitted to Congress and approved. Congressional Joint Resolutions on international affairs can be found on Congress.gov (filter by Bill Type: Joint Resolutions and Subject: International Affairs).