For me, music-making has two phases -- sound-making and song-making. These are two very different disciplines. Sound-making is fun and spontaneous. Song-making can be those things too, but it also becomes extremely detailed and deliberate as the song inches closer to its final version.
Sound-making exists in many forms. It may be a playable instrument sculpted inside of a synthesizer, where sound-generators produce waveforms that are modified and shaped by other processing units. It may be an existing recording, be it a movie, music, or anything else, then chopped up and placed in a sampler to be held indefinitely until called upon to play again. It may be a sound made here at home or in some faraway place, created and recorded with the sole purpose of being used in a composition in the future.
Song-making assembles the prior work of sound-making, and organizes it into a composition. Songs are layers of sounds. Keys, chords, rhythmic patterns, notes, effects, and changes in all of those things through time are the focus in song-making. Because of the complicated intertwined nature of the sounds in a song, a deep focus really helps here. For me, song-making can only really happen if I know I have at least 8 hours of contiguous time to devote to it. The more the better.
A typical song takes me 20-40 hours of song-making time. I may have only spent a couple hours with sound-making, or I may have spent a month collecting and producing sounds. Only when there is an emotional reason coupled with inspiration from the toolkit of sounds can a song happen.
Here's part of what it looks like when it's done...
The horizontal rows are different sounds or instruments. Time passes from left to right. The lines and curves in this image are different parameters of the sound or instrument that will change over time. These parameters may be as simple as the loudness of the sound, or as nuanced as the level of resonance in a particular filter within a complex subtractive synthesizer. Any and all of these thousands of possible parameters can be "automated" or controlled by drawing lines on the screen. This is where a lot of my time goes in song-making.