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.
The Maurya period is remarkable in the early history of the Indian subcontinent. Chandragupta Maurya was the first ruler who tried to consolidate small fragmented kingdoms and combined them to form the first empire of the Indian subcontinent.
EXAMIANS