Bilateral Agreement - means an agreement between two countries.
Multilateral Agreement - means an agreement between three or more countries.
Extradition Treaty - is a formal agreement between two or more sovereign States that details when and how a formal request for extradition will be honored. There can be bilateral and multilateral extradition treaties.
Example of multilateral Extradition Treaty - The European Convention on Extradition, The London Scheme for Extradition with the Commonwealth, the UN Model Law on Extradition
Mutual Legal Assistance Treaty (MLAT) - is the formal cooperation between two or more sovereign countries for the purpose of gathering and exchanging information in an effort to enforce public or criminal laws. There can be bilateral and multilateral MLATs.
Example of bilateral MLAT - United States and Canada; United States and Italy; United States and Thailand
Example of multilateral MLAT - European Convention on Mutual Assistance in Criminal Matters, ASEAN Treaty on Mutual Legal Assistance in Criminal Matters