Lots of students have asked me some variety of that question: “What’s the difference between arranging and improvising?”

Remembering that language is fluid and not everyone means the same thing with the same term, still there are some basic understandings about the difference between the two. Basically improvising indicates the creation of a melody which is significantly different than the written tune, while arranging keeps the same melody, but uses different stylistic devices to create a new sound or a new feel to the song.

Watch this short video and I think you’ll understand quickly.

For a course on arranging, look into How To Dress Up Naked Music. For a course on improvising, look into the Seven Month Course In Piano Improvising.