Hi @yorkpf, thank you for your question.
You are correct that the LSST has six filters, ugrizy. These bands do not exactly match the SDSS bands. For a quick comparison, see the relevant plots below, which are from Filter Response Curves — speclite v1.0.1.dev3.
If you’re looking for more information or would like access to the transmission curves themselves, the best place to start is the left-hand menu bar of the “for scientists” page at For Scientists | Rubin Observatory. There you will find a link to Filter Throughputs which takes you to a GitHub repository of filter transmission curves (GitHub - lsst/throughputs: LSST Simulations repository for baseline evaluation information · GitHub). As the readme file describes, the LSST throughput curves are in the “baseline” directory, and those are the ones you should use to, e.g., calculate expected magnitudes. For a more detailed comparison of various filter systems with the LSST filters, and/or code to use to make plots like the ones shown above, visit Filter Response Curves — speclite v1.0.1.dev3.
Thanks again for posting your question, and if you have any further questions on this topic please don’t hesitate to reply to this thread.