Each GUI command can have up to three Lua equivalents. The "single" equivalent works on a single segment, and the "all" equivalent works on all segments. For the band functions, there are likewise "single" and "all" versions.
The "selected" equivalent works on selected segments. The Lua functions selection.Select and selection.SelectRange select segments. A recipe also inheirits selections the user has made in the selection interface.
There's no "selected" option for bands in Lua V2.
The "single" classification is used when there's only one function. For example, Add bands can add bands between many pairs of segments. Similarly, Reset Puzzle affects everything at once, not just a single segment or band.