Viharas were for the purpose of living, Chaityas were assemblies for the purpose of discussions. Further, Chaityas were with Stupas, Viharas did not have stupas.
Universal soul is one of the main Keystone of the philosophy and the thought of the Upanishad. Brahma satyam Jagat Mitya Jeevo Bramanah Parah talks about the impermenance of the body and its existence.
EXAMIANS