Non-Resident (External) Rupee (NRE) account is a rupee account from which funds are freely repatriable. It can be opened with either funds remitted from abroad or local funds maintained in NRE / FCNR accounts, which can be remitted abroad. The deposits can be used for all legitimate purposes. The balance in the account is freely repatriable. Interest credited to the NRE accounts is exempt from tax in the hands of the NRI.
Non-Resident Ordinary Rupee (NRO) account is a rupee account and can be opened with funds either remitted from abroad or generated in India. The amounts in such an account are generally non-repatriable. However, funds in NRO accounts can be remitted abroad subject to/as per various directives in force at the time of repatriation. More details can be found on the Reserve Bank of India (RBI) website www.rbi.org.in