Under "Tools" click "Compare structures". In iScienceSearch you need to have a structure displayed in the drawing window, or a CAS number, chemical name, or other chemical identifier in the text box.
We only can compare structures from sources that deliver us structure files. These are at the moment NCICADD, PubChem, and ChemSpider. The ChemSpider service is under construction by ChemSpider and does not work always.
This shows some of the different structures for taxol in PubChem.
You can group by InChI key and get a clear overview of the many different structures. We recommend looking at the InChI key to distinguish complex structures.