This 51% includes Arab Christians (in Israel and the terretories), Arab Muslims (in Israel and the Territories), and Druze (in Israel, minus those in the Golan territory which are Syrians) 47% are Israeli Jews of different races, ethnic backgrounds and Jewish denominations (affiliated, secular, orthodox, reform, etc). The other 2% are "other" Muslim non-Arabs (eg. Ciracassian) and "other" Christian non-Arabs (eg. Armenians), and non-Arabs of other religions. This means, that the Jewish minority is ruling over a non-Jewish majority. That makes it a minority ruled region. What makes it an apartheid is the fact that the laws of the region are applied differently to different groups of people based either on Religion or ethnic affiliation, or both.
Western-backed Syrian rebels say kill foreign Islamic State (Reuters)
from the article: Israel denies offering nuclear weapons to Apartheid South Africa