Bilateral Trade:

The trade that takes place between two nations is called bilateral trade. In this trade, the member nations exchange their goods and services with one another on a preferential basis, based on an agreement, a bilateral trade agreement. In bilateral trade, the countries involved enjoy a number of privileges like favorable import quotas.

Multilateral Trade:

Multilateral Trade Agreement refers to the trade agreement that is executed among multiple nations to buy from and/or sell to one another preferentially or a country may be in agreement with several countries to trade with the rest of signatories, either preferentially or on terms restricting trade among themselves. Multilateral Trade Agreement is a trade treaty  among various nations. This promotes the global economy, by opening markets for both developed and developing countries.

Bilateral aid:

Bilateral aid is the dominant type of state-run aid. Bilateral aid occurs when one government directly transfers money or other assets to a recipient country.

Multilateral aid:

Multilateral aid is like bilateral aid, except it is provided by many governments instead of one. A single international organization, such as the World Bank, often pools funds from various contributing nations and executes the delivery of the aid.