It seems to me that if the things are different, then they have to have a different name. Otherwise how would you differentiate between them?
Ethnic cleansing: removal of a group due to their ethnicity from a piece of land. The result: this group of people stays alive, but has to go to a different place.
Genocide: physical extermination of an ethnic group. The result: they are all dead.
Why these two distinct events should have the same name???