* Size and Trim: The Star Chief was the larger, more luxurious model. It featured more prominent tailfins, more elaborate chrome trim (especially around the grille and side), and generally a more upscale interior. The Laurentian was smaller and had a more streamlined, less ornate appearance. Think "bigger and flashier" for the Star Chief, "sleeker and more understated" for the Laurentian.
* Grille: The grilles were significantly different. The Star Chief's grille would be more expansive and likely have more intricate detailing. The Laurentian's grille would be simpler. Pictures of 1959 Pontiac grilles are readily available online for comparison.
* Tailfins: While both had tailfins, the Star Chief's were taller, wider, and more prominent. Again, visual comparison with online images will be highly effective.
* Badges and Emblems: The most definitive way: Look for the badging. The car will clearly display "Star Chief" or "Laurentian" somewhere on the exterior (likely on the trunk or fenders).
In short, size, trim level, grille design, tailfin size, and especially the badging itself are the key differentiators between a 1959 Pontiac Star Chief and Laurentian sedan. Using online images of both models from that year will help tremendously in identifying your car.
