It's hard to pin it down to one set of requirements, but I'll try.
Caves with some short (as safe as a cave) old mined bits fall under cave categories, e.g. Carlswark Gin Entrance. Digging that opened a cave is still classed as a cave.
Mines are proper abandoned mines with more mine than cave, and they all present hazards typical of mines. Jugholes, being predominantly cave, has sections of mine with plenty of hazard to be managed, and hence it goes on the mine list for the LCMLA scheme.
Most places are more clear cut, and there is a specific list of all possible mine sites (and caves) that award holders can potentially have listed on their award on the JustGo system for registered award holders. Oh, I suppose I should also mention to those that don't know, that LCMLA holders can only lead in sites they have listed on their award and have specifically done local knowledge or practical assessments in. It's only CICs with the ability to work in any cave or approved mine without the need for it to be named on their award certificate.