Account Balance: 

The Account Balance is the amount of money in a  Partner's Account. It reflects transactions such as Credits, Reimbursements and Debits. When you credit/issue funds to a Partner's Account, the Account Balance will increase. 

When you reimburse or debit funds from a Partner's Account, the Account Balance will decrease. 

Available Balance: 

When a Partner submits a request to use the funds in their Account and the request is moved to the approved (funds allocated) step in your workflow, the Available Balance will reflect this event. The Available Balance is the Account Balance - the approved/ allocated amount. 

Available for new MDF Requests Balance:

The Available for new MDF Requests Balance is the Account Balance - MDF Requests that have been approved (funds allocated) and those that have not yet been approved (new or open requests)