Deferred Expenses is another name for Prepaid Expenses: costs a business has already paid in cash but has not yet consumed, so the benefit is deferred and recognised as an expense gradually over the period it is actually used, rather than all at once when the payment was made. A twelve-month insurance policy paid for upfront, for example, is recorded as an asset and expensed one month's worth at a time as each month of coverage is used up.
Why two names exist
Both terms describe the identical accounting treatment and the identical line item on the balance sheet: an amount already paid that sits as a current asset until it is gradually recognised as an expense. “Prepaid Expenses” emphasises that cash has already been paid out; “Deferred Expenses” emphasises that recognising the cost on the income statement has been deferred to future periods. Which label a given company or textbook uses is simply a matter of convention, not a difference in meaning.
Where to go for the full explanation
See Prepaid Expenses for a full explanation of how these amounts are recorded, how they are released to the income statement over time, and common examples such as prepaid insurance, rent and subscriptions.