Dry: below 0.9% residual sugar, FG under 1.002
Semi-Sweet: 0.9% - 4.0% residual sugar, FG between 1.002 - 1.012
Sweet: above 4% residual sugar, FG over 1.012
Still: No or little carbonation
Petillant: moderate carbonation level
Sparkling: highly carbonated
Even dry still ciders will tend to have bubbles. The biggest distinction you can make is that a petillant cider normally continues to rise with carbonation without giving an obvious carbonation that comes with sparkling cider. Still cider will often have some small bubbles upon release, but quickly dissipate.