Although these terms often seem to be used interchangeably, there is a difference between them. "Migration" is the umbrella term and refers to movement in general, although it can also denote seasonal movement, of either people or animals. The terms "immigration" and "emigration" are only used in reference to people, and they both imply a more permanent movement, as in a permanent relocation. You immigrate
to
a place and emigrate
from
a place. All three words are are feminine in the French, and the only difference in spelling is that there is an
accent aigu
over the "e" in
émigration
.