What is an editing pack, and how is it different from my editor's project?

An editing pack holds recordings that belong together, with how they are stitched: stabilization, horizon, lens colours and the other settings. On the virtual drive each editing pack is a folder, Editing packs\<name>, where its recordings appear as video files.

Your editor's project, in DaVinci Resolve or Adobe Premiere Pro, is where you cut. It imports the video files of an editing pack. One editing pack can serve several editor projects, and one editor project can use files from several editing packs.

In Two Left Wheels 360, the ? next to Editing pack in the main window explains the same. See Create an editing pack and add recordings.