Vinyasa is all about connection with movement and breath to allow yourself to explore the inner spirit. There's nothing quite like heavy breathing, body heat and good vibes to get you more connected with others and of course yourself. Vinyasa classes generally start and end with mindfulness and reflection. Between this you'll experience a range of sun salutations or 'flow', peak postures, sweating and stretching, this all then winds you down for your savasana (final meditation).
Nidra is commonly described as yogic sleep. Nidra is traditionally a guided meditation generally lying down that allows the individual to gain profound levels of relaxation. Unlike sleep, you remain conscious during nidra but if done effectively you can feel refreshed as if having fully rested.