It appears to be related to the Norwegian "stor". I enjoy finding connections like these. https://en.wiktionary.org/wiki/stor#Norwegian_Bokm%C3%A5l
So are there rules for making adjectives comparative?
So in English, old becomes older, hard becomes harder etc, and as I understand it, старый means old, while старше means older, yes?
So if I replace the ый with ше in a similar adjective, does that make it comparative? Or is that too much simplicity to hope for?
It is correct to translate it as "elder brother", and Duolingo accepts this. However "older" can also be used within the family, if the person is also considered "old". Hence I can say "my older uncle" (who is 90) as well as "my elder uncle", but not "my older grandchild" (who is presumably still "young")