Question: Species with different arrangements of atoms but having no structural differences?
Answer: isomer
Disambiguated annotations:
qaPairs: question: Species with different arrangements of atoms but having no structural differences and which are non-superposable mirror-images of each other?
answer: enantiomers
question: Species with different arrangements of atoms but having no structural differences and which are not non-superposable mirror-images of each other?
answer: diastereomers