BLR(Base Lending Rate) is set by the central bank, and current BLR is 6.75% while fixed rate is set by the financial institution, normally they have a certain limit when you do the prepayment, you will be charged once you exceed the limit.
Different bank may give you different BLR rate, but 1 thing that I can tell you here is ABN AMRO Bank always give the lowest rate. (app 6.0%-6.5% )
See the graph here:
<a href="http://imdavidlee.com/2008/04/25/different-home-loan-package/">imDavidLee.com</a>
May i know what's the different??