Tracks
The linear sequence of clips for an instrument
With Synfire, the narrative Structure of your composition should be your primary focus, because linear Tracks for each instrument (as in a DAW) are built from that structure automatically. A track is simply the sequence of Clips that results from the arrangement of containers. When you move containers around, all tracks are rebuilt for you.
Containers can be nested and clips may contain any kind of parameters, so it is not immediately obvious on the Structure page what's ultimately landing on a track. The Tracks page Is therefore a convenient map to navigate and understand your final result.
Structure vs. Tracks
In the Structure view, you can focus on building suspense and overall musical experience, while the details of each individual track are automatically handled for you in the background. The structure view makes it particularly easy to make sweeping changes, experiment with ideas, and try out alternatives, all non-destructively. In the flat and linear tracks view, this would be extremely tedious (which is why we often avoid doing this in a DAW).
Thinking of music as a structure has real creative benefits, although it takes some getting used to. Of course, you can still build a song on the Tracks page, as you would do in a DAW. However, the resulting container structure will then be more like a pile of clips that makes little sense.
To clean up the mess in hindsight, you can build a structure from flat tracks by using to group related clips, such as “Verse,” “Chorus,” “Middle Part”, and then consolidate the containers.