Barriers to successful harmonisation of accouting standards?

I believe this question is phrased incorrectly. "International Accounting Standards" means the same thing as IFRS. IFRS stands for "International Financial Reporting Standards". I suspect the question should actually read 'what is the difference between IFRS and US GAAP? I have some knowledge regarding this question as well but this is by no means a complete response. The piece I know about applies to the treatment of R&D expenses. Under US GAAP, almost all of a company's R&D expense are treated as cash outflow (expenses) and affect the income statement in the period in which they occur. There is no effect to asset levels on the balance sheet. Under IFRS, a large portion of a company's R&D expenses must be capitalized and then depreciated/amortized over some period. The treatment is more like that of capital investment spending and creates assets on the balance sheet that then carry a book value as they are depreciated over time.