Question: Species with different arrangements of atoms but having no structural differences?
Disambiguated questions and answers: question: Species with different arrangements of atoms but having no structural differences and which are non-superposable mirror-images of each other?
Species with different arrangements of atoms but having no structural differences and which are not non-superposable mirror-images of each other?
answer: enantiomers
diastereomers
Natural Questions answer: isomer (from the Wikipedia article "Isomer")