Biggest difference is that the horse will have shown signs of colic or distress long before rolling. Anxious, looking at their sides, straining to make manure, pawing, elevated pulse and respiration, possibly sweating.
Most horses will roll after a workout, and will hunt around, nose to the ground, looking for a good scratchy place. My chestnut horse is a diva and *must* roll if he's the least bit sweaty, always rolls after a bath or being unsaddled. It's a *happy* roll, if that makes sense.
A colicky horse rolling is not a *happy* roll, and the horse will be showing clear signs of distress beforehand.