I think you misunderstand these terms. A digital nomad is most certainly not an immigrant. An immigrant moves someplace with the intent to stay and live there working and becoming a member of that society. (Even if they never become a citizen of that country.) In contrast a digital nomad moves someplace with the intent to stay for only a short time. They will work virtually the same job they have in their home country. Likewise an expat is someone that is only residing in a country, typically for a job posting from their job in their home country. Neither of these last two have any intention of becoming a part of the society of the country they are living in and they are most certainly not immigrants.