Theravada Buddhists are those who stick to the Pali Canon. Mahayana Buddhists accept many developments in Buddhist thought and practice that took place later. In this course we are concentrating on a development associated with the "Perfection of Wisdom" (Prajña Paramita) tradition. Ch'an/Zen Buddhism is a form of Mahayana Buddhism relying heavily on the Perfection-of-Wisdom teachings.
Differences between Theravada and Mahayana teachings regarding Enlightenment are more a matter of emphasis than disagreement on basic issues.
1. The Pali Canon is focused entirely on the process of reaching Nibbana or Enlightenment. It seldom speaks of what it is like to live life in the state of Nibbana. It is very clearly addressed to monks and nuns living in monasteries, teaching them the path to Nibbana. It does not describe what it would be like to live a normal social life in the state of Nibbana.
Mahayana Buddhism, especially in its Zen version, often pictures what it is like to live life in an Enlightened state. Teachers in this tradition give examples of how Buddhist teaching relates to ordinary life problems that affect everyone. For example, we have some letters written by the medieval Chinese Zen teacher Ta-Hui giving advice to a Confucian official experiencing political difficulties:
I have heard that there was some complicated situation in the past and now you are experiencing the sadness of the outcome... Usually [to meditate] you set your mind on a still concentration point, but you must be able to use it right in the midst of the hubbub. If you have no strength amidst commotion, after all it's as if you never made any effort in stillness... If you consider quietude right and commotion wrong, then this is... seeking nirvana, the peace of extinction, apart from birth and death... When you like the quiet and hate the hubbub, this is just the time to apply effort... (Cleary 1977: 27-28)
There is nothing like this in the Pali Canon. "Householders" (non-monks) are given moral advice, but not educated in Buddhist spirituality or meditation practice. This can can give the impression that Theravada teaching encourages monks and nuns to become dependent on the quiet of monastic existence and avoid the "hubbub" of ordinary social life. But careful thought about the teaching of the Pali Canon should make one realize that deep and inflexible dependence on quiet surroundings is an example of Tanha/Upadana. The more peaceful existence in a monastery is helpful for a person trying to bring about the transformed state of mind called Nibbana, but if they really make substantial progress toward this internal transformation, this should make them less dependent on particular surroundings or a particular lifestyle, and able to rise to any occasion presented to them by a more stressful life outside the monastery.
But this is a point not emphasized in the Pali Canon itself.
2. A very careful reading of the Khandha-teaching of the Pali Canon would lead one to realize the principle that anything which is opposite to something belonging to the khandhas also belongs to the khandhas. An upset feeling belongs to the feeling-khandha, as does its opposite, a calm feeling. A mind preoccupied with thoughts belongs is a mental "condition" belonging to the conditions-khandha, but its opposite, a blank mind, is also a mental "condition" belonging to the conditions-khandha. This should be clear if one reflects on the fact that deep and inflexible dependence on reaching a calm or blank state of mind would cause additional dukkha if one could not reach these states on some given occasion.
But this point is easily overlooked because it is not emphasized in the Pali Canon. Reading the phrase, "... Therefore the noble student turns away from feelings" (in the an-atta passage cited earlier), a reader who is not careful could easily understand this to mean, "Have no feelings. Blank your mind."
The Mahayana Perfection of Wisdom teachings make this mistake less likely, because their main purpose is to correct this particular mistaken understanding, so they are very explicit and emphatic about it. This mistaken understanding is the main characteristic of what they refer to as "Hinayana" Buddhism.
On the other hand, it is worth noting that a great deal of Mahayana writing is written by Mahayana teachers to correct other Buddhists who also officially belong to "Mahayana" sects, but who are also making this "Hinayana" mistake. The Hinayana mistake is made by almost all beginning Buddhists, even those belonging officially to the Mahayana branch. The Zen Patriarch Hui-Neng corrects this Hinayana mistake of his rival in a Zen monastery. Shunryu Suzuki is concerned to correct this mistake among his Zen Buddhist students.