Primary lymphoid organs are those that undergo maturation/ differentiation into antigen-specific lymphocytes.
In bone narrow and thymus, and both provide the micro-environment for the development and maturation of beta-lymphocytes and lymphocytes.
Secondary lymphoid organs are spleen, lymph, nodes, tonsils etc. The lymphocytes interact with the antigen and proliferate to forma a clone.
Antigens trapped in them activate the lymphocytes present in the lymph nodes and produce an immune response.