Be sure to check FCC Part 97.305 for frequency allocation differences. For example;
IARU's band plan calls for all mode operation on 40M from 7060 - 7300 kHz. FCC part 97 restricts Phone and image transmissions down to 7125 kHz.
Per 97.305
Phone and Image also allowed between 7.075 MHz - 7.100 MHz
Obviously, the FCC's current rules by which we U.S. radio amateurs are governed by, must be the rules we follow.
There are a number of Region 2 countries that really don't have a FCC equivalent for radio amateur frequency and mode guidance, so the IARU guidelines are important to them.