Timeless (non-rhythmic): used to fill space, off-sync with the song / tempo.
Rhythmic: matched to fit a particular beat / note duration.
Delay: distance between original attack and repeat(s).
Mix: volume of repeats.
Feedback: number of repeats.
Tone: eq of repeats.
Spill-over: the delay 'finishes' it's repeats, even after you bypass the unit.
Kill-dry: the output contains only the repeats (used with a parallel effects loop, rack units, wet/dry setups, etc.