The account report shows the amount of revenues and expenses during the month for each account, the balance shows what the current balance for that account (the balance depends on the historical incomes / expenses relative to that account).
For example, for the bank, in June I spent $ 1190 and earned $ 1,500, a difference of $ 310 (this amount is what you see in account report). If at the end of May I had $ 190 at the end of June I will have $ 190 + $ 310 = $ 500 that is the balance in the June.