Plasma cosmology and mainstream cosmology differ in their explanations of black holes, pulsars, and galactic formation: - Plasma cosmology explains black holes as plasmoids, pulsars as electrical arcs between binary stars, and galactic formation as interactions between cosmic currents and plasma clouds. - Mainstream cosmology explains black holes as regions with strong gravity and accretion disks, pulsars as spinning neutron stars, and galactic formation through theories like MOND and existence of WIMPs. - While plasma cosmology views the universe as predominantly plasma, mainstream cosmology is based on Einstein's field equations and gravitational theory.