Only Nubians, Sudanese Arabs from the Eastern provinces, and the Beja are close to Horn Africans (Ethios/Somalis). Especially the Beja tribe are ethnically the closest.Hararboy, are people from Sudan also considered Cushitics, since they look very similar to East Africans?
Other Sudanese (like South Sudanese, Copts, Darfurians, Nubas, Berta, Fulanis, Hausa, Gumuz etc) are not close to Horn Africans overall. There are big racial differences within Sudan. Here is a study that analyzed the Sudanese in detail: