Yick Wo v Hopkins, 1886
....Even though the Chinese laundry owners were usually not American citizens, the court ruled they were still entitled to equal protection under the Fourteenth Amendment.
“The rights of the petitioners, as affected by the proceedings of which they complain, are not less because they are aliens and subjects of the emperor of China… . The fourteenth amendment to the constitution is not confined to the protection of citizens. It says: ‘Nor shall any state deprive any person of life, liberty, or property without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.’ These provisions are universal in their application, to all persons within the territorial jurisdiction, without regard to any differences of race, of color, or of nationality; and the equal protection of the laws is a pledge of the protection of equal laws… . The questions we have to consider and decide in these cases, therefore, are to be treated as involving the rights of every citizen of the United States equally with those of the strangers and aliens who now invoke the jurisdiction of the court.”
The rights of non-citizens have been reaffirmed by the Supreme Court on numerous occasions since then....when the rights are limited to citizens (ie right to vote or hold office), the Constitution makes a clear distinction between citizens and "the people".