Superbowl winner Marshawn Lynch says Jarryd Hayne failed to make it in America because of the cultural divide between the NRL and NFL.

The code-hopping league star left the San Francisco 49ers in May in a bid to qualify for the Rio Olympics with the Fiji Rugby Sevens team.

Lynch, in Australia to promote the US College Football season opener in Sydney this weekend, said while he was in awe of Hayne, there was too deep of a cultural chasm for him to cross.