How do the physical features of mainland Southeast Asia compare and contrast to those of island Southeast Asia ? How do the physical features of mainland Southeast Asia compare and contrast to those of island Southeast Asia ? Solution mainland southeast asian has more chinese influence. geographically chinese went there first before they spread. while islander southeast asian has mixture background of indian-arabs-chinese-polynesian-europian.back in 5-600 years ago those islands were transit ports for every sailormen from around this world.finally because of the tectonic plates too. .