The XT-TG Tom-Tom Gate has 2 special features that you won't find in a regular gate:
The XT-TG learns the tom-tom's sonic character which helps the XT-TG separate the tom hits from the other drum hits nearby. It then only triggers on the the drum "strike", and not sympathetic resonances with other drums.
Learns the sonic characteristics of the Tom sound.
Learns the sonic characteristics of the surrounding "spill" sound.
The Hold control is the length of time (ms) the XT-TG will remain open, once it has been triggered, allowing you to determine how much or how little of the Tom "ring" you allow though before the XT-TG begins to close.
The Release control determines how long (ms) it takes for the XT-TG to close fully once it starts to close.
The Depth control sets how many dB of gain reduction is applied when the XT-TG is closed.