Some Japan players are paid £13 a day while on tour, says coach Jamie Joseph.
Amateur players based in Japan receive 2,000 Yen (£13.54) a day for their northern hemisphere autumn tour, while England players earn £25,000 per cap.
Japan, the hosts of the 2019 World Cup, face England at Twickenham on Saturday at 15:00 GMT.
Joseph, 48, said his players have "different motivators" to the larger nations and that the amateur players are "employees of companies".
He added: "To be here and play a team like England is a great opportunity for a footy team and a footy player.
"Our professional players - the foreign-based players - don't get paid for playing for Japan.
"They do it because they want to play a high level of rugby that they don't get in Japan."
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England head coach Eddie Jones, 58, guided Japan to a 34-32 victory over South Africa in the 2015 World Cup, the greatest win in their history.
Former New Zealand international Joseph said Japan have a lot of "respect" for Jones, despite the England boss warning them to "pray" before this weekend's match.
Joseph said: "Eddie Jones has also coached club rugby over there for many years and has got a lot of relationships. We have got a lot of those players here.
"He was an established coach in Japan for many years. When I was playing there he was coaching. He is a great coach."
England beat South Africa before losing to the All Blacks in their autumn internationals.
They face Australia on 24 November, while, Japan finish their European tour against Russia at Gloucester's Kingsholm Stadium on the same day.