Classic vs Volume Lash Extensions
Classic lashes are one extension applied to one natural lash. The result is your own lashes, just longer and darker. It's the "she looks well rested" set, and it's the best place to start if you've never had extensions.
Volume lashes are handmade fans of multiple ultra-fine extensions applied to a single natural lash. Because the fibres are lighter, you get far more fullness without extra weight. This is the fluffy, dramatic, obvious set.
Hybrid sits between them, mixing classic lashes and volume fans for texture that's fuller than classic but softer than full volume.
Mega volume uses the finest fibres and the largest fans for the darkest, densest look available.
Weight isn't the deciding factor, your natural lashes are. Sparse or fine lashes often suit volume better, because fans distribute weight more evenly than a single thick classic extension. Your tech will map it at your appointment.