Simply put, it's just that the Sabres jerseys from 1970 to 1996 featured a much more vibrant shade of blue.
They changed it in 1996-97, despite literally no one wanting that.
And somehow, 23 years of fan screaming later, they STILL haven't put it back to the way it was.
It is, perhaps, the most protracted avoidance of easy fan service in the history of fan service.