What are the differences between GAAP based and Pro Forma financial statements?

Question:

What are the differences between based and Pro Forma financial statements?
GAAP
Generally Accepted Accounting Principles (GAAP) is the accounting standard adopted by the U.S. Securities and Exchange Commission (SEC). While the SEC previously stated that it intends to move from U.S. GAAP to the International Financial Reporting Standards (IFRS), the...