Namaste toujour,
thank you for the post.
hmm... off hand, i do not know of any, however, i will search for some.
essentially, the difference between the schools in Tibetan Vajrayana at any rate, is some different terminology and a slightly different emphasis on Tantric teachings.
there is another path within Tibetan Buddhism called Ri-me, which is an integration of all four schools of Tibetan Buddhism. you may have some interest in that sort of thing so this site should prove useful, and it has a brief overview of all the schools:
http://www.nalandabodhi.org/tibet_buddhism.html
here's an excerpt:
[FONT=Arial,Helvetica,Univers,Zurich BT][SIZE=-1]1. The Nyingma School
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The Nyingma, or "old school," traces its founding back to the initial phase of Buddhism in the 7th to 9th century, and is thus called the old school. Some of the main teachers who established the Nyingma lineage are set forth above, the leading figure being [/FONT]
[FONT=Arial,Helvetica,Univers,Zurich BT]Padmasambhava[/FONT][FONT=Arial,Helvetica,Univers,Zurich BT]
. [/FONT]
[FONT=Arial,Helvetica,Univers,Zurich BT][SIZE=-1]2. The Kagyu School
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The Kagyu school primarily traces itself to the Indian mahasiddha Tilopa and his disciple Naropa. Naropa in turn taught Marpa Lotsawa, a great translator who journeyed from Tibet to India three separate times to study with Naropa. Marpa's main disciple was Milarepa, who's main disciple was Gampopa. One of Gampopa's main disciples was the first [/FONT]
[FONT=Arial,Helvetica,Univers,Zurich BT]Karmapa, Dusum Khyenpa[/FONT][FONT=Arial,Helvetica,Univers,Zurich BT]
. One of the meanings of Kagyu is "command lineage" which emphasizes the oral instructions passed down from teacher to student. [/FONT]
[FONT=Arial,Helvetica,Univers,Zurich BT][SIZE=-1]3. The Sakya School
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The Sakya school traces itself to the Indian mahasiddha Virupa, who transmitted the Buddhist teachings to his student Drogmi Sakya Yeshe, who in turn taught Khon Konchog Gyalpo. The latter built a monastery in Tibet near land named "Sakya," and the lineage name derives therefrom.[/FONT]
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[FONT=Arial,Helvetica,Univers,Zurich BT][SIZE=-1]4. The Gelug School
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The Gelug, or Gandenpa, school traces itself to its founder Tsong Khapa, who revitalized the Kadampa teachings of Atisha, and combined them with teachings from texts transmitted during the second wave of Buddhism's transmission to Tibet. The Dalai Lamas are members of the Gelugpa school. [/FONT]
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[FONT=Arial,Helvetica,Univers,Zurich BT]
The Sakya, Kagyu and Gelugpa are "new schools," established during the second wave of Buddhism's transmission from India to Tibet in the 11th and 12th centuries.
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[FONT=Arial,Helvetica,Univers,Zurich BT][SIZE=-1]Rime Movement[/SIZE][/FONT] [FONT=Arial,Helvetica,Univers,Zurich BT]
In general, the lineage traditions are supported by different, independent Tibetan institutions. Each of these major schools were predominant in Tibet during different periods of Tibetan history, and each have geographical areas where they are more popular. There are also innumerable subschools and divisions within each of these four major schools, a tendency which is heightened by the individual nature of lineage transmission. Still, many unifying movements have informed Tibetan institutions over the centuries. In particular, in the Nineteenth Century, the Rime movement led by Jamgon Kongtrul the Great and the great Jamyang Khyentse, revitalized many Sakya, Nyingma and Kagyu institutions by promoting respect and knowledge by each of the other.[/FONT]
metta,
~v