Those would be more properly called 'audio descriptive subtitles'.
Life would be a whole lot easier if they always called them what they actually are but it's impossible to tell as they don't name them consistently.
Sometimes it's very clear and you see 'English - Director's commentary' or 'English - Audio descriptive' etc indicated but it's quite common to see them all just marked as 'English' with no clarification at all.
If there are forced subtitles then you can normally be fairly sure they're for the foreign language bits but it's so easy to check this by playing them that it's best to confirm this if you intend on removing all the other subtitle streams rather than finding out later.
TBH though the subtitles occupy such a very small amount of space that I usually just copy all the English ones and leave the default subtitle behaviour as it is.