The major differences between Mahayana tradition and Theravadan tradition in Buddhism include the number of Buddhas, the proper language to use for religious texts, the number of bodhisattvas, and the acceptability of adaption of local custom.
Mahayana Tradition recognizes an infinite number of Buddhas who are able to help people achieve enlightenment or, for the lay followers, pray to in times of need. Theravadan tradition however only recognizes Gautama Buddha and prior Buddhas as legitimate. These Buddhas are accepted as men who found enlightenment, but not as supernatural beings. The Mahayanan tradition of accepting infinite Buddhas is beneficial to the religion overall because general practitioners can look to the different Buddhas for guidance and support in times of trouble which, in turn, has a profound positive influence on lay followers.
Theravada Buddhism only accepts Maitreya Bodhisattva as an “official” bodhisattva because he is the only one mentioned in the Pali language cannon. However, Mahayana teaches that all human beings have the opportunity to become a bodhisattva through many lifetimes worth of work. This act of becoming a bodhisattva is seen as an act of great compassion in Mahayanan tradition because the practitioner forestalls an easier road to nirvana to help others achieve enlightenment. Mahayanan tradition holds those who forestall their own ascension to nirvana in the highest regard; however, Theravadan tradition rewards those who focus on their own attainment of nirvana. As a result, Theravadan Buddhism tends to be seen as an elitist religion without much in the way of benefit for lay followers.
Theravadan Buddhism also does not allow local input or updating of traditions from the original Pali language; however, Mahayana allows local traditions to blend with the prior tradition. Mahayana also accepts all languages as part of their cannon while Theravada only allows for the original Pali texts as cannon. Theravadan furthers compounds this difference by only allowing the Tripitaka to be written in Pali unlike Mahayana’s acceptance of all languages. Without a blending of traditions and the ability to easily adopt the ideals of Buddhism to each new region or group, Theravadan Buddhism has had a much harder time spreading over a large area. Mahayana however, has continually spread, and, as a result, has become the dominant form of Buddhism in most areas.
Theravada tradition puts only minor emphasis on rituals. The rituals that are practiced only come from pre-Buddhist influences; local customs are cast aside in the practice of Theravadan Buddhism. Mahayana however greatly emphasizes rituals most of which are based on the local traditions of the area Mahayana migrated to. Emphasis on rituals causes Mahayana to be seen as a folk religion or words over substance and it also encourages the dilution of Mahayanan tradition with the influx of outside influences.
The differences within Mahayanan schools of Buddhism are striking. The three main schools: the pure land sect, the intuitive sect, and the rationalist sect each offer three very different but complementary views of Buddhist scripture and philosophy. Theravadan tradition has only a single school of thought which prevents the philosophy from being fully explored by practitioners. However, Theravadan tradition does have strength as it does not have the schisms in the religious community that has plagued Mahayanan tradition since its inception.
Overall, Mahayanan tradition is seen as a religion of the people while Theravadan tradition is a religion of the elders. Neither is entirely superior to the other as both traditions have their own strengths and weaknesses.