I think this is an issue with non-native english trying to understand the terminology.
A discharge tube is a category of lighting, the most common being the High Intensity Discharge lamps and neon tubes:
![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d3/Edelgase_in_Entladungsroehren.jpg/1920px-Edelgase_in_Entladungsroehren.jpg)
There are a number of variants and the device you linked to is supposed to be a somewhat universal power supply for them.