"Apartheid wall" is a popular name for the security barrier (which is mostly actually a fence) constructed around the West Bank. Some say it is also designed explicitly to steal land; this is disputable. What is not disputable is that "apartheid wall" is a wholly illogical name for it.
Apartheid was a system that existed within one country, as the South African state was sovereign over both the white and non-white populations. Hence, the proper level at which to reform apartheid was at the level of South Africa as a whole: not through the creation of two states, but one, reformed state. As the whole world constantly reminds Israel, its military occupation of the West Bank is not an expression of legitimate sovereignty. Rather, the solution is rightly understood to be two states, one Israeli, one Palestinian, living side by side. It is illogical to talk of "apartheid" between two populations who do not even share a country.
This is not a technicality because of the growing number of people who foresee a "one-state solution" in which Israelis and Palestinians are indeed subsumed into one country. As the Israeli refrain goes, this country would either be "not Jewish, or not democratic"; perhaps surprisingly, this "solution" is hence touted by Arabs, who foresee that the most likely eventual outcome would be their own control of Israel itself because they will soon outnumber the Jews between the Mediterranean and the Jordan.
It is no coincidence that we have hence seen a marked increase in a discourse that labels Israel as "apartheid" rather than as an imperial occupier, because it encourages a solution within the framework of one state. This discourse should be rejected as surely as we reject Israeli attempts to undermine a two-state solution when they appear.