To see differences, click onto the Plant Database and search for sedum and then sempervivum to see the differences and in some cases, the similarities.
My simplified version of the differences: Though both sedum and sempervivums are succulents, they differ somewhat in form. Sempervivums tend to be stemless and generally are rosette in shape with many leaves surrounding the growing center. Sedum can have closely clustered leaves along stems or widely separated leaves on stems. Flowers for each genus vary distinctly.
