What are the comparision and differences of TSCA and FIFRA?

The Toxic Substance Control Act (TSCA) covers all chemical substances, regardless of what they are used for. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) covers only substances used for those purposes. For example, FIFRA might cover a particular insecticide product, but it would not cover the precursor ingredients. Those would be covered by TSCA.