Hīnayāna (हीनयान) is a Sanskrit term literally meaning: the "Smaller Vehicle", applied to the Śrāvakayāna, the Buddhist path followed by a śrāvaka who wishes to become an arhat. The term appeared around the 1st or 2nd century.
Mahāyāna (Sanskrit: महायान mahāyāna, literally the "Great Vehicle") is one of two (or three, under some classifications) main existing branches of Buddhism and a term for classification of Buddhist philosophies and practice.
Vajrayāna (Sanskrit: वज्रयान, Bengali: বজ্রযান) is also known as Tantric Buddhism, Tantrayāna, Mantrayāna, Secret Mantra, Esoteric Buddhism and the Diamond Way or Thunderbolt Way. The Lama and the Guru yoga are central in this system.