Both the NRE & NRO Accounts are designed for taking care of the financial needs of an NRI (The Non-resident Indians) keeping in view of the sources of income wherein,
1. The NRE A/c are referred to as "Non-Resident External", A/c being opened in India in order to keep and manage their income earned by them in the foreign countries. This a/c facilitates conversion of foreign currencies into INR or Indian currency allowing an NRI to maintain foreign currency earnings in Indian Rupees also. In addition, these accounts are exempted from tax and the A/c holder can repatriate the money any time.
2. The NRO A/c. are referred to as "Non-resident Ordinary" which is a bank account opened in India in order to keep and manage the income earned by them in India, like rent, pension, dividends, etc.
Pl. note that unlike NRE accounts, the NRO accounts are not exempted from tax laws which means the income tax, wealth tax, gift tax, etc., are applicable to NRO Accounts while in the earlier one it's not. In addition, the interest rates would vary in the both the accounts depending upon the offers made by the respective banks.
Fluctuation in the exchange rates is also a major difference that lies within these two accounts wherein the NRE accounts having an implication, the NRO accounts are safe.
Adding with another difference within these two then, funds originating from a foreign country can be deposited in both NRE and NRO accounts but the funds originating from within India can only be deposited in NRO accounts.
The similarity within these two however lies in terms of withdrawals of money which only can be made in Indian Rupees or INR.
This is important for our note that there are many leading and well-known banks, both in the public sector as well as in the private sector which offers this facility of NRE and NRO Accounts. The list can include the SBI, ICICI, HDFC, Kotak Mahindra, etc. to name a few.