Balance in account and FlowToken

Hi there ,
I am new to Flow , thanks anyone can help.
I want to know the difference between account.balance and FlowToken.Vault{FungibleToken.Balance}.

I got account.balance by execute command in Flow cli is different from the value I got from executing following script.

acct1.getCapability(/public/flowBalance).borrow<&FlowToken.Vault{FungibleToken.Balance}>()