Full flexi:

1) current account tied to loan account
2) auto debit from current account at month end and interest is calculated based on outstanding balance minus amount in current account
3) maintenance charge of RM10 per month
4) setup/ processing fee of Rm200 (certain bank)
5)The liquidity comes in the form of an ATM card or a linked CASA account to the housing loan. 
Example: You have a shop that is opened Monday to Satuday, rest on Sunday. On Saturday, you deposit all your proceeds of the week into the flexi account, on Sunday, you would save [(your-HL-interest-rate)/365]*AmountDeposited worth of interest. On Monday, you withdraw the money to run your business
6) Withdrawal of money or crediting of money through ATM,CHEQUE,OVER THE COUNTER, or online

Semi Flexi

semi flexi package typically has these features:
1) requires you to phone in to indicate the extra payment as early settlement of advance payments
2) if you fail to indicate, you will be charged 1% (some banks do this afaik)
3) if you indicate advance payment, no additional interest is saved as "advance" payment will only be credited to your loan account when it reaches your cycle date, so it is plain advance payments. and must be in multiple of your monthly payment.
4) For redrawable prepayments, you need to indicate separately and Redraw charge of RM50 is imposed (M*B charge Rm25)
5) Withdrawal of money or crediting of money through Cheque or Over the counter