According to Osho, mahavrata is not a bigger quantity of renunciation but the inner breakthrough where unconsciousness and the very mind of possessiveness drop; then non-attachment flows naturally. Anuvrata is practiced restraint while the mind still clings—fighting oneself in steps. Outward acts may look alike, but the test is: does it happen by itself, or by effort? True renunciation is a living capacity to let go.
Mahavrata is when the “mine, mine” feeling is gone so you let go naturally; anuvrata is when you still want to hold but practice letting go.