It's because the US clearly is the main supporter of Israel who is the Goliath in that conflict.

In Sudan the US is not clearly propping up one side.

People are reasonably more mad in the US about Gaza since their taxes directly fund it and the US seemingly could exert influence on Israel if there was political will.

It is not clear how the US would improve Sudan without wading into some massive peacekeeping / reconstruction mission - which no one has the appetite for.

It’s the religion not the color that’s the factor. If oppressor belongs to a certain religion it’s all kosher. If the roles reverse it’s genocide.