Ni hao 木叶丸,
to emigrate:
to leave a country permanently and go to live in another one .
Millions of Germans emigrated from Europe to America in the nineteenth century.
to immigrate:
to come to a different country in order to live there permanently.
He immigrated with his parents when he was a child and grew up in France.
Immigration include also animal and plant life ,you could say :
" Only few plants can immigrate to the island" ,meaning migrating to a new environment .
So the difference is basically :
He immigrated to --------- .
He emigrated from ---- to -----.
He who emigrates also immigrates. As he leaves his country of origin, he emigrates from his homeland, in order to immigrate to another country. Leaving his old country, he is an emigrant, but arriving in his new country, he is an immigrant.
I hope the difference is clear now:)