Mahayoga is called “great yoga” because it is considered to be superior to other yoga Tantra. The scriptures of Mahayoga are divided into sadhana sections, with texts for meditation on particular deities and a Tantra section.
In Mahayoga, the practitioner visualizes him/herself as the divinity with consort. It is important that the visualization is clear and precise. Through the visualization, all phenomena are recognized for what they truly are -- a display where appearance and emptiness are the same thing.
In yoga practice, maha may also refer to the maha bandha, which is the "great energetic lock." In maha bandha, all three energetic locks are performed at once -- jalandhara bandha, uddiyana bandha and mula bandha.