Places tag - red dot vs white dot

[Billy5FE5]

In my list of places tags, some have a red circle in the middle and some have a white circle. 

Does anyone know what the significance of this is?

Thanks in advance, 

Billy.

[MichelBParis]

In my case, the icons with red dots have subfolders which can be expanded while those with white dots don't have any sub-levels.