Cash Flow Statement is simply another, commonly used name for the Statement of Cash Flows, one of the three core financial statements alongside the balance sheet and the income statement. The two terms refer to the exact same report: a record of a company's cash inflows and outflows during a period, broken into operating, investing and financing activities, which together explain how a company's cash position changed from the start to the end of that period.
Why two names exist
Accounting standards formally refer to the report as the Statement of Cash Flows, and that is the title that appears in a company's official filings and audited financial statements. In everyday business and finance conversation, however, it is just as often, if not more often, called the cash flow statement, and the two terms are used completely interchangeably by analysts, lenders and business owners. There is no difference in content, structure or purpose between the two — only the name differs depending on the formality of the context.
Where to go for the full explanation
See Statement of Cash Flows for a complete explanation of its three sections — operating, investing and financing activities — how it is built, and why it is used alongside the balance sheet and income statement to judge a company's actual cash-generating ability rather than just its reported profit.