It is an nominalized adj. When not referring to things with gender, but rather to abstract things, it takes the neuter declensions. Here, etwas has no gender mark, so Andere- must be declined so to mark that it's a neutral form... I don't know if I've made my point clear. For example, gut is an adj, but can be nominalized (an then is capitalised) Das Gute = the good (the "das" already marks the gender). Alles Gute = all the good (again the gender is marked in the word alles). Etwas Gutes = something good (the word etwas says nothing about the gender so the word "Gute" takes an -s to mark the gender).
Hope this helps a little.
I was about to write the same translation as you. In the last moment I have changed it, considering that it is better (from to Duolingo point of view) to respect as much as possible the meaning of each word. I was right from Duolingo point of view. Still, I have the same question like you. I would dare to answer to your question with "yes". The common-sense is supporting an "yes" answer.
The sense for each of the 2 mentioned variants is quite similar, hence the confusion. Beside, I think "Gibt es" wasn't used within Duolingo until this phase. I learn this expression later, from a book. Of course, it make sense what you say, if you already know about "Gibt es", but if you don't?...Well, if you don't, I think the above question is understandable. It's not about brain capabilities, it's about knowledge...
I'd suggest: "is it something different?" , even though I miss what the question refers to,e.g: Are You mad at me , because I came home drunk with lipstick all over, or "ist es etwas anderes?
while: is there sthg else; You'd like to buy translates into: ist da noch etwas/gibt es noch etwas,....