Explanation:

The Coinage act 2011 which took over Coinage act 1940 says "necessary provisions for inclusion of Government of India one rupee note within the meaning of ‘Coin’ have been consciously incorporated in the Coinage Act, 2011. Further, the RBI, as per Section 24(1) of the RBI Act, 1934, is not empowered to issue bank note of denomination of value of one rupee"

Further, "apart from the metal, the coin may be made of any other material,”
Hence according to the act One Rupee Note is a 'coin'. Also, in accordance with the RBI Act 1934, RBI can not mint coins.

What are the implications of One Rupee note to be classified as a coin.

One Rupee Note is an asset, just like other coins. So "I promise to pay the bearer." is not written on the note. You already hold an asset. While RBI Notes are a liability.
One Rupee Note and One Rupee coins are legal tenders for unlimited amounts. One rupee defines the unit of the currency! It is the base of the currency system.
A 1000 rupees RBI note says "I promise to pay the bearer the sum on one thousand rupees". Hence RBI notes which are a liability promises to pay you an asset. This asset is defined by "One rupee"
So, the Government of India has the power to mint/print 1 Rupee coin/note which are an asset and define the unit of currency. RBI notes get the value from the asset known as 'Rupee'.