A track I wrote for a contest on the FL Studio Looptalk forum, with a "Light & Darkness" theme. The track starts with a piano playing a melody over some D minor chords, and by the end it is playing the same melody with a D minor - F major - C major - Bb major progression. That change in chords and character of surrounding instrumentation is what I hope gives the difference between "Darkness" and "Light". With a build section between them, of course! ;)
As a fun fact, I the only synth/instrument I used was FL Studio's "FLEX" (free for all FL Studio users); furthermore, I only used sounds from the "Magnificence" bank by Sense Gemini (also free for all FL Studio users). I used a fair bit of automation, both on effects (all standard in FL Studio) and synths.