Most traditional Kung fu schools have no color belt/sash ranking system at all as far as I know. And I have never seen a Northern style with one. But that does not mean they do not exist.
And those that do I highly doubt the colors are the same since you can see different color ranking system between Jujitsu and Karate TDK and Judo, Karate and karate, etc.
Must don't and those that do unless from the same lineage the color can mean anything. We wear a blk sash in Hak Fu Mun, but it carries no rank.