How does MPLAB® Harmony differ from Microchip Libraries for Applications (MLA)?
MPLAB® Harmony is the next generation of Microchip software libraries. These new libraries have been designed to be modular and interoperable and can easily work with a Real Time Operating System (RTOS).
The older Microchip Libraries for Applications (MLA) is similar to Harmony in terms of the applications it supports (USB, TCP/IP, etc.) but these libraries were not designed for interoperability. Integrating MLA libraries requires more software development time to remove conflicts (peripheral access, function, resource, and variable namespace) between these libraries.