This is where severums are tricky. Domestic, tank-raised green severums are said to be
Heros efasciatus, but in actuality they could be a whole mix of things. I've kept efasciatus, notatus, and rotkeil here at my house, and they all interbreed readily. This means that tank-raised fish can be a mix of all three. The only way to know for sure would be to know the lineage of the fish, and that's just not possible with fish that you pick up from LFS most of the time.
Then consider that turquoise severums,
Heros appendiculatus, are no longer considered a separate species and have been folded back into the efasciatus group with greens, and you open a new can of worms. IMO, the turquoise fish are different from greens. But (for now) science says they're the same fish.
What you end up with are "green" severums that range from brown to green to blue, with varying characteristics that could include black spots, bars, no bars, dark maroon anal fins, bright red anal fins, orange anal fins, red, orange, or yellow eyes, etc. A "green" severum doesn't necessarily have to be green in color. It can be a wide array of colors. It's just a common name, the same way "gold severum" is a common name for severums that range from white to yellow to bright red.
All juvenile severums that I've raised (efasciatus, notatus, and rotkeil) show a light tan/gray/green body with black vertical bars. This does not change until about 4" when the adult coloration starts to come in. Sometimes the bars will fade and the fish will be solid tan, gray, or green.
Here is a 4" juvenile rotkeil. You can see that the red color starts slowly as red dots just behind the eyes and gills.