Thus I have read ( ), the question was posed by the user "Shadow Dancer" in January 2007:
The Rev. Eijo responds:Hello. I remember when I was looking at information on Vajrayana Buddhism and Tibetian Buddhism that Shingon was the other major school of Vajrayana. Out of curiosity in what ways in this tradition similar to Tibetian Buddhism and different? Also is the book Bardol Thodol of interest (I don't mean on an individual level) to Shingon Buddhists? Or is it viewed as something purely for Tibetian Buddhists?
Hmm. Since the East Asian esoteric Buddhist traditon is older than the Tibetan, I consider Tibetan Vajrayāna the "other" form. Just kidding, I know what you mean
Setting aside the issue of whether or not it is appropriate to call Shingon "Vajrayāna,", and not really knowing the level that you are asking your question at, the basic differences might be summed up as:
1. There is no anuttarayoga-tantra in Shingon, and none of the practices and iconography associated with it. Shingon has what corresponds to the kriyā, caryā, and yoga tantras only. Shingon practices no form of "sexual yoga" at all.
2. The system mentioned above of classifiying tantras into four categories is not used in Shingon. Instead, in Shingon tantras are classified into zōmitsu 雑密 and junmitsu 純. Zōmitsu practices have mundane goals, like practices praying for blessings, health, the prosperity of the nation, good harvests, rain making, the ability to memorize Buddhsit texts and so on. Junmitsu practices are for perfecting the Mahāyāna bodhisattva path. Both exist in Shingon, with junmitsu being the main practice and zōmitsu existing as a form of skillful means.
3. Shingon lacks Tibetan cultural influences, and has instead East Asian cultural influences.
4. Japan had no significant awareness of even the existence of Tibetan Vajrayāna until the 19th century. Since the Bardo Thodol was composed in Tibet, it is utterly unknown to the East Asian tradition. It was first known of in Japan from the Japanese translation of Evan-Wentz's English translation.
5. Not really part of Vajrayāna, but since we are comparing the Shingon and Tibetan traditions, I might note that Shingon doctrinally does not give the most emphasis to Mādhyamika thought. Traditional Shingon doctrinal studies involve a number of areas, including Yogācāra and Mādhyamika in their East Asian forms, called Sanron/Sanlun 三論 and Hossō/Faxiang 法相. To go out on a limb, Shingon thought is perhaps closest to Kegon/Huayan 華嚴 thought. Its practice is not that of Huayan, however; it is tantric practice. Deity yoga is the core practice of Shingon.
There are many details about practice which are different between the two, but with many major features being generally the same. If you can be a little more specific about what you wanted to know, I might be able to answer in more detail.