You need to obtain these standards and review them to learn the differences. EN 10002-1 is 54 pages long, while ASTM E 8M is 22 pages long. We can't summarize them for you in a short reply. In general, you can obtain the actual mechanical properties of a material using each method.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.