Arabs israeli citizens in Israel are second class citizens. They are not legible for civic duties, meaning they are not trusted to engage in the most fundamental aspects (security apparatus) of the state. Ethiopian and Sudanese Jew migrants (many of whom converted to Judaism over 2000 years ago) are being kicked out as we speak.
Also Islam isn't a race and Saudi Arabia is highly diverse. Over 10 million Saudis and Saudi Residents (30%) are not from Saudi Arabia but recent arrivals from Egypt, Yemen, north africa etc. Pakistanis and Indians form the biggest non-arabic groups comprising up to ~4 million; then you have millions of non-arab natives of the Middle east, such as Berbers, Beduins, other north-africans etc.
Arab citizens of Israel have full rights and can get whatever job they want, many are doctors, lawyers, politicians etc... Also many Arabs serve in the IDF, a Druze IDF memeber was on that was shot at the gates of the Mosque last year.
Israel isn't kicking out any Ethopians, they actually went through great pains to bring them to the country, Operation Samson should ring a bell. The issue is with illegal migrants which many have crossed from Egypt a safe 3rd country to enter Israel illegaly. And they haven't kicked anyone out yet and the issue is very decisive in Israel as seen by the protest there.
Judaism isn't a race either, and everything you said to point to Saudi's diversity is true for Israel. It has people from all over the world in its country, from Egypt, Yemen, Iran, Morocco, North Africa, USA, Canada, EU, Russia etc... Saudi still priortizes ISlam, and Islam makes up close to 100% of its population while Israel is only a smidge under 80% Jewish.
And I don't have a problem with Saudi wanting to maintain and Arab and Islamic side to its country. Its the birthplace of Islam and of Arabs so I would think they would want to continue to that represent their culture. Just like Israel is the birth place of Judaism and the Jewish nation.
Not every ethno state is going to be white supremacist who want all POC's dead. Sometimes an ethno state is actually preferable. People like to be with their own and mixing people together can lead to great conflicts. Its why we don't have a Czechoslovakia anymore and same with the break up of Yugoslavia into separate countries.