When comparing IFRS and GAAP, what are some overall key differences I should be aware of?

Below is answer:

Because of longstanding convergence projects between the IASB and the FASB, the extent of the specific differences between IFRS and GAAP has been shrinking. Yet significant differences do remain, most any one of which can result in significantly different reported results, depending on a company's industry and individual facts and circumstances. For example: • IFRS does not permit Last In, First Out (LIFO). • IFRS uses a single-step method for impairment write-downs rather than the two-step method used in U.S. GAAP, making write-downs more likely. • IFRS does not permit debt for which a covenant violation has occurred to be classified as non-current unless a lender waiver is obtained before the balance sheet date.