An isomer (/asmr/; from Greek , isomeres; isos = ''equal'', meros = ''part'') of a molecule has the same number of atoms of each element, but has a different arrangement of the atoms. It has the same molecular formula as the other molecule, but with a different chemical structure. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are two main forms of isomerism (/asmrzm, as-/): structural isomerism (or constitutional isomerism) and stereoisomerism (or spatial isomerism).

What's the best answer to this question: could two molecules contain the same sets of atoms but have different properties?
yes