While their operating principles are unclear, disruptors seem to perform much like phasers. While equally effective, the damage they inflict tends to be more mechanical in nature -- ripping or tearing of affected material -- than that of phasers (TNG, "Hero Worship").
Disruptors of either scale can fire pulses or continuous beams.
- "It's not just an effective weapon. It's... vicious. It tears a body apart... and very slowly by your phaser standards."
-- Kivas Fajo describing a Veron-T disruptor, TNG "The Most Toys"