The difference between your 1099-B and your transaction list could be the result of Wash Sale Loss adjustments reported on your 1099-B. A wash sale occurs when an investor sells or trades a security at a loss and purchases “a substantially similar one” 30 days before or 30 days after the sale. The loss on the sale is disallowed. It could also be the result of transactions that are not reported on Form 1099-B, but are included in the transaction list. This would include certain option trades. You could also have non-qualified transactions where the broker is not required to report the cost basis to the IRS, so it is not included on the the 1099-B, but it is included on the transaction list.
There is no standard for "Transaction Lists" like there is Form 1099-B. You will have to compare the two side by side and/or contract your broker to determine what the difference between the two.