Denemo is a free software graphical interface for music notation, mainly to GNU LilyPond, a program for engraving musical scores.
License: Open Source
OpenMPT is primarily a music tracker designed for audio editing and sample management, making it suitable for electronic music production, while Denemo is focused on music notation and score editing, ideal for composers and musicians looking to create sheet music. Both are open-source and free to use, but they cater to different aspects of music creation.