The main difference between the organization IAEA and the CTBTO is that CTBTO is a comprehensive organization of all states in the world while IAEA only includes member states. CTBTO regulates production of nuclear weapons worldwide whereas IAEA ensures that states producing nuclear weapons cooperate.
The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) was established in 1997 by the homonymous Treaty, the CTBT, signed in 1996, which bans all nuclear explosions anywhere by anyone. The CTBTO is building and operating a network of 337 monitoring stations and laboratories located in 89 countries and the Antarctic region. This network of seismic, hydroacoustic, infrasound and radionuclide stations is currently 85% in operation and it monitors the globe for signs that can give away any clandestine nuclear explosions. Data are gathered by the stations, sent via a satellite network to the CTBTO headquarters in Vienna for analysis and then disseminated to all the Member States of the CTBTO, currently the 182 countries that have signed the Treaty. Upon entry into force of the CTBT, On-Site Inspections could also be requested by any state on the event of a suspected nuclear test which then has to be approved by the CTBTO Executive Council Composed by 51 States representing all regions. Once approved these inspections are obligatory for the inspected state.