hi nagalakshmi! I would just like to add some more info here.
now that Dezyre have defined exactly what sundry debtors and creditors are, let's view this from a practical perspective.
sundry debtors and creditors Groups in Tally ERP 9 have been programmed to behave just the same for small debtors/creditors (i.e. sundry) and for large debtors/creditors (those parties who are big enough to be assigned individual accounts). both these groups are sub-groups of current assets as you must be knowing (create a ledger for sundry debtors and you will see that when you select sundry debtors it will show current assets with it as main group).
so that means that you can group all large and small parties under sundry debtors and creditors. if they are parties who don't use bills/invoices but for e.g. just keep your running balance record with them (like some small stores do) you can in
tally set the 'Maintain Bill-by-Bill' option to NO for these kind of parties. For other parties you can set this option to YES.
Also if you like accuracy in description (as all accountants do) you can rename the Sundry Debtors/Creditors Group to Trade Debtors/Creditors and create another Sundry Debtors/Creditors Group using Sundry Debtors/Creditors as its name. This group you can use for parties with whom small and infrequent purchases are made and with whom you don't exchange a lot of documentation.
I have divided my Debtors and Creditors into Trade and Non-Trade for easy identification of transaction types. Trade group includes those from whom we purchase or make sales of our raw materials and products. Non-Trade are those from who we purchase or sale things that we don't use in our business trade e.g. office supplies, stationery, office pantry stocks etc.
Hope this helps. If you need further help do let me know. Cheers!