This is why common names are a problem in the hobby. “Red shoulder” or “rotkeil” are both names for Heros sp. rotkeil, an as-yet-undescribed species out of Peru. “Rotkeil” is German for “red wedge” and describes the area of red coloration behind the head and neck of the fish. The fish has also been sold as raspberry face, raspberry nose, rainbow severum, orange shoulder severum, red neck severum, etc. etc.
“Red tiger” is a trade name coined by Oliver Lucanus for Heros severus before they were formally identified. These are much larger, more aggressive Heros from Colombia, Brazil, and Venezuela. They also go by Curare as the original imports by Oliver were from the Curare region of Venezuela — not all severus hail from there, so it’s actually incorrect to label all of them as such. Unfortunately once a trade name sticks it’s hard to correct.
There are differences in Heros sp. rotkeil and Heros severus but they are subtle in juveniles and the diagnostic features are not 100% all the time. For instance, most wild-caught rotkeil have only 8 vertical bars, while most other Heros species have either 8.5 (severus) or 9 (efasciatus, notatus, liberifer, appendiculatus, etc.). But hybridizing in the hobby has led to commercially-bred rotkeil that show 8.5 or 9 bars. Ditto for wild Heros severus — most show 8.5 bars, but nearly every imported batch contains fish that also have either 8 or 9. Then you have the issue of aberrant barring; some fish have bars that are forked, fused, crooked, etc. which is a fairly normal occurrence in wild populations. Not all fish have perfect markings or the “correct” markings as the species are described.
Your young fish could be either rotkeil or severus. (It could also be Heros sp. Inirida but that’s less likely than the other two so we’ll skip that for now.) The markings look like a young severus — the wide gap between the 8th and 9th bar where the half-bar should be looks like severus. Also, the faint black spotting arranged in vertical columns which are overlapped by the solid black stress bars is typical of severus. But young severus are not common in the hobby and it would be weird to find them randomly mislabeled as rotkeil somewhere.
Wait until the fish is about 4” and post it in a new thread asking for opinions. By then the body shape and patterning should start to reveal more about its identity.