The map thing is often mentioned on gifted checklists, especially in regards to kids recognizing shapes of countries out of context (DD did this--Dora's hair looked like some country, an odd wooden salad implement looked like another, toast and pancakes often looked like countries...)
I remember a boy next door who knew everything there is ever to know about trains. I don't think he was on the spectrum although he was not exactly friendly with me or my siblings. I don't think it's uncommon for young children to get into a subject and become an "expert" or a collector of facts at a young age.
That to me is a different skill set than your DD's ability to make connections as a toddler.That divergent thinking skill seems more indicative of advanced cognitive abilities and creativity to me although having an excellent memory always helps in the learning process and two skill sets are definitely not mutually exclusive.
It makes sense that school work comes very easily to your DD. She probably has the memory and critical thinking skills to learn whatever she sets her mind upon.
