* mark single article as read
* mark single article as unread
* mark all articles on page as read
* mark all articles on page as unread
The difference between marking a single article and marking all articles seems to be based on how far you've swiped, but if (for example) you don't release your swipe and keep moving your finger further after it's marked all as read, it suddenly does the opposite and marks all articles as unread. The direction of the swipe (left or right) doesn't seem to control whether you're marking read/unread -- it's (in my experience) been completely arbitrary what it decides to do, regardless of swipe direction. It's ridiculous how painful it is, and it's basically been this way for as long as I can remember.
This can be looked at as a continuous race to see who can build the highest-throughput computer, where the competitors' positions in the race are decided based on a well-defined set of benchmarks. The periodic updates don't indicate who's won -- they're just a snapshot of what everyone's positions are in the race around the time of publication. So it's more apt to say one competitor is ahead of another in the race, but talking about winning or beating someone maybe gets more clicks.