When watching Amending Fences, when we first see Moondancer and Twilight as fillies they seem very similar. But that conversation I think showed their differwnces.
How Moondancer read ahead hoping to help Twilight only for it to turn out she had the wrong book. You can see how embarassed Moondancer was.
I have a theory Moondancer while smart wasn't too organized unlike Twilight. Also as shown in her later life not as tidy and clean as Twilight.
Overall I see Moondancer as someone who looked up to Twilight as a role model. But Twilight seemed more annoyed with her presence.
>>930172p
I bet Moondancer felt like Twilight was a snob who was too good to hang out with someone like her and it betrayed her hope in humanity.