I'm not sure about a difference of lp gain between people from different continents. However the lp loss (on sunday night) is different for players from NA then for EU players. The lp loss is calculated so that the 1st players has 95k and that only 100 (or something else) players stay at e9, 1000 at e8 and more at e7. As they are way less players in NA, the NA players lose less lps (or even none) as they arent 100 e9 players.
If you take a look at this player from NA, you can see that he stayed at 90000 lps for several months until he started playing again. This scenario is completely different for this EU player who didnt play for 2 weeks.
NA player not playing staying at 90k (10.11.14 -> 6.6.15) :
http://www.maniaviewer.com/?site=player ... titleId=26
EU player, 105k at 8.7.15 -> 85k at 20.7.15 :
http://www.maniaviewer.com/index.php?si ... ogin=nampo
Solution : Make the ranking global, the top ladder is composed of more than half players with a fake country