A detailed description is available from the Reserve Bank of India website.
NRE accounts a Indian rupee accounts that are freely repatriable to your foreign bank account at any time. Interest earnings in NRE accounts are not taxable in India.
NRO accounts are Indian rupee accounts that function much like resident savings accounts. Interest earnings in NRO accounts are taxable in India. Repatriation upto USD 1 million (check this) per year are permitted from NRO accounts.
You can use money from both NRO or NRE accounts to invest with Scripbox. We have no preference. However, if you are a tax resident in India, we recommend you consult a tax accountant on re-designating your NRE and NRO accounts to resident Indian accounts.