Differences between 移民 and 移居
移民(v) immigrate; (n) immigrant

移居(v) migrate; move to ~ (to live)


移居中国= move to China (to live) 


You just need to move to China to quality as 移居, even you don't become a citizen of China. Since it is very likely for someone 移居 to a country will later become an immigrant to that country, "移居" can also implies "to immigrate". 

If you just move from Beijing to Shanghai, you are definitely not "移民"(immigrating) from Beijing to Shanghai; you are "移居" (migrate to) Shanghai from Beijing


移民中国 = immigrate to China - You are expecting to become a Chinese citizen
中国移民 =  Chinese immigrant
移居 is not a noun, therefore, there is no such thing as 中国移居