You are talking about citizens. The crime of apartheid, as defined by international law, has nothing to do with citizenship. Citizenship is not a criteria for the crime of apartheid to happen.
The term “apartheid”, an Afrikaans word, derived from the French term “mettre à part”, literally translated to “
separating, setting apart.” Apartheid is a policy that is founded on the idea of separating people based on
racial or ethnic criteria.
Imposing restrictions in movement, application of different laws for Israelis and Palestinians for the same crimes in the West Bank, the land grabbing, instituting and maintaining a system that is structurally designed to keep people apart, the law of return applying to Jews who
never lived in present day Israel (it would
even apply to me today if I were to convert to Judaism) but not to the Palestinian refugees or their descendants, who DID live in the land FAR LONGER than most Israelis (even in the 1940s) etc are considered apartheid. And Israel is guilty of it. Here is an entire PDF on it.
Amnesty International has analysed Israel’s intent to create and maintain a system of oppression and domination over Palestinians and examined its key components: territorial fragmentation; segregation and control; dispossession of land and property; and denial of economic and social rights. It...
www.amnesty.org
Here is a great documentary if you are too lazy to read a PDF. Infact this documentary draws parallels between South Africa and Israel.