Yeah, but they're completely tied together nonetheless, what with Daniel Hall being Carter "Hawkman" Hall's grandson and all. Several other ties as well.
I think Gaiman knew DC would want to use the Lord of Dreams after his Sandman series ended, which is why he replaced him with the white-haired one by having Daniel "grow up" suddenly. Now DC can use the Lord of Dreams, but Gaiman can still keep his character really "his", y'know?
BTW, the Sandman also made a brief appearance in the AMBUSH BUG NOTHING SPECIAL back in the early '90s. It was pure Giffen.