The Open Source Initiative gave collaborative source development a new name, a formal definition and a licensing-review process designed to communicate its practical value to businesses and institutions.
Copyleft used copyright law in an unusual way: instead of only restricting copying, it granted broad freedoms while requiring redistributed modified versions to preserve those freedoms.
The BSD licensing tradition allowed source and binary redistribution with minimal conditions, creating a model in which open code could move freely into academic, open-source and proprietary systems alike.