I hope someone can clarify something for me.
This course uses बड़ा for big and for old, छोटा for small and young.
I understand how this might work for children, as generally the older they are the bigger they are. It also works for siblings - in English my younger brother is my "little" brother even though he is taller than me. But I wouldn't call friends who may be a year younger than me "little". Likewise I may have a "big" sister, but if I said any other person was bigger than me I would be talking about size, not age.
So is it the case in Hindi that an adult friend who is छोटा than me might be smaller or younger? And conversely, an adult who is बड़ा than me might be bigger or older, but we don't know which? (Or perhaps we do know in context, it is only in isolated sentences that we don't know?) Or would we, in reality, use different words to describe age and size of adults who are not our भाई बहन ?
I'm not mother tongue, but when talking about friends I'm pretty sure छोटा and बड़ा would be interpreted as small/big (as opposed to siblings, where it could be both).
Ex: कैसे हो मेरा छोटा दोस्त? How are you my little friend?
It just doesn't seem to me there would there would be many instances where you really want to stress that a friend is younger/older, but if you ever did then the words would be (I think) जवान/बूढ़ा. You could say वह मुझसे जवान है (he/she is younger than me).
Here are some examples from this course, which lead to me asking the question in the first place.
"ये लोग बहुत बड़े हैं।" Suggested translation: These people are very old.
"वह तुझसे छोटा है ।" Suggested translation: He is younger than you.
"These people are younger than you." Suggested translation: ये लोग तुमसे छोटे हैं।
So in each case, if it was a real situation, it would be obvious how the बड़ा and छोटा were being used, whether for size or age. But to a learner with just these context-less sentences to understand, it is at times confusing.