Skating : the sport of gliding on skates; The action or sport of moving along a surface (ice or ground) using skates.

Skate : sports equipment that is worn on the feet to enable the wearer to glide along and to be propelled by the alternate actions of the legs.

Roller, Quads, Inline Sating, Blading - what's the difference ? 

Roller Skates

Roller Skates are devices worn on the feet to enable the wearer to glide along on wheels propelled by the legs. Roller skating is traveling on smooth terrain (not ice) with roller skates. It is a form of recreation as well as a sport, and can also be a form of transportation.

Roller Skates generally come in two basic varieties: inline skates, and traditional quad (roller) skates, though some have experimented with a single-wheeled "quintessence skate" or other variations on the basic skate design.

The basic types of Roller Skates (for Ground)
Quads ( Roller Skating)

The four-wheeled turning roller skate, or quad skate, with four wheels set in two side-by-side pairs, was first designed in 1863 in New York City by James Leonard Plimpton in an attempt to improve upon previous designs. The skate contained a pivoting action using a rubber cushion, and this allowed the skater to skate a curve just by leaning to one side. It was a huge success, so much so that the first public skating rink was opened in 1866 in Newport, Rhode Island with the support of Plimpton. The design of the quad skate allowed easier turns and maneuverability, and the quad skate came to dominate the industry for more than a century.

Inline or Blades for Inline Skating / Blading

Inline skates are a type of roller skate, used for inline skating. Inline skates have two, three, four or five wheels arranged in a single line. Some inline skates, especially those used for recreation, have a "stop" or "brake" which is used to slow down while skating; most inline skates have a heel stop rather than the toe stop, particularly indispensable for Inline Figure Skating.