HELLO GAUTHAM
snq quota Supernumerary Quota (SNQ) are for the students who are economically weak.
Well there is nothing like differents seats fore SNQ quota its just that if your family income is less than 6,00,000 rs p.a and you have a proof of it like income certificate Tahsildar or the Block Education Officer and submit it at the document verification stage of the examination then you can avail this quota whether you are from general category or any.
the only limitation is all can get SNQ quota keeping in mind the above condition but it is only given to the students based on their merit
suppose if you get a seat in xyz college and you have SNQ quota enabled and you are in merit list then the entire government fees is waived off for an eligible candidate and s/he only has to pay a token amount for other costs.
HOPE IT HELPS!!