The standard installer creates a brand new (clean) operating system on the disk, deletes the existing OS, and restores the compatible applications.
Erase and Install is similar except that the disk is wiped prior to installing the new system, and existing applications/settings have to be restored in a separate process from a Time Machine backup.
ie: it's a three step process; the standard installer simply combines the three steps into a single installation procedure.
Probably, there's not a nickel's worth of difference between the results of the two methods, although the Erase and Install seems like it might take longer to complete.
BTW, I noticed that initially, SL graphics performance seems below par.
After a few hours, the standard installation returns to normal performance.
This seems to be true for all OSX systems that include Spotlight.