Full members have decision-making power as well as voting rights and play a direct role in shaping the agenda and policies of BRICS. They participate in high-level summits, where key decisions regarding economic cooperation, international governance, and political strategies are made.

Full members have greater influence over BRICS institutions like the New Development Bank (NDB) and the Contingent Reserve Arrangement (CRA), shaping the policies and projects funded by these institutions. In terms of economic and trade, full members benefit from deeper trade, investment, and economic collaboration with other BRICS members, such as preferential trade agreements or joint infrastructure projects. Full members have greater diplomatic and political alignment as part of the core decision-making process, which allows them to align with other major economies and advocate for reforms in global institutions (e.g., the International Monetary Fund or the United Nations) from a position of strength.

Partner countries do not have voting rights or formal influence over the internal decisions and policies of BRICS with limited decision making. Their role is more collaborative but less authoritative. Partner countries can benefit from collaboration on specific projects, investments, and access to resources like funding from the NDB for infrastructure or development projects, though they do not have full control over such funding or access to economic and development initiatives

The partner member allows for flexible engagement without the responsibilities or obligations of full membership. Countries can work with BRICS members on specific issues such as trade or research but are not bound by the same level of political and institutional commitment. Partners enjoy economic, trade, and diplomatic ties with BRICS countries, but the relationships are usually not as deep or comprehensive as those of full members.

TLDR; Full Members get to influence and vote in stuff inside BRICS. The partners will receive most of the benefits, but will not be able to influence or vote, nor do they need to be ideologically closer to the BRICS members.