In formal source of credit the borrower have to go give collateral to the bank or any source, but in informal source of credit there is no need of such thing but they have to give high interest as compare to formal source of credit.
Formal source of Credit means the Loan which we take from banks and informal source of Credit means which we take from landloards or zamidar

People obtain loans from various sources. The various types of loans are grouped as formal sector loans andinformal sector loans.Formal Source: (i) These include loans from banks and cooperatives.(ii) The Reserve Bank of India supervises the functioning of formal sources of loans.(iii) The rich households avail cheap credit from formal lenders.Informal Source: (i) It includes moneylenders, traders, employers, relatives and friends, etc. (ii) There is no organisation which supervises the credit activities of lenders in the informal sector. Compared to the formal lenders, most of the informal lenders charge a much higher interest on loans.(iii) The poor households to pay a heavy price for borrowing from informal sources.
Formal sources-banks and financial institutionInformal sources – relatives and friends and family