On a Sparc, a disk is divided into slices and the term "partition" is not used. On a PC, a disk is cut into "partitions" so this is the fundamental division of a disk. You often have multiple OS's on a PC with each getting its own partition. Solaris will take its partition and again divide it into slices. On either a Sparc or a PC, a slice is what gets mounted. (This assumes no volume manager is in use.)