No, it is not the same. One can be an immigrant and not a expatriate.
That is this entire thread, including the OP, with whom you seem to agree. Why have you not complained to tkiolp4 that they are just quibbling over technicalities? To be frank, I rather suspect it's because "quibbling over technicalities" is something that does not concern you, except as it can be a convenient excuse to dismiss an argument you don't want to engage with intellectually.