I  want to know  that  what  is  the  "difference"   between  
'personal   guarantees   and  bank   guarantees' so  as  to  obtain  
real   estate  financing ??

Personal Gurantee

Promise made by an entrepreneur which obligates him/her to personally
repay debts his/her corporation defaults on.

Bank guarantee

A guarantee from a lending institution ensuring that the liabilities
of a debtor will be met. In other words, if the debtor fails to settle
a debt, the bank will cover it.
A bank guarantee enables the customer (debtor) to acquire goods, buy
equipment, or draw down loans, and thereby expand business activity or
purchase a home.