yes they are both home cinema systems, but both slightly different.
the HT-SF1300/2300 is an amp/speakers pack,with tall floor standing speakers,and seperate subwoofer.
the HT-SS models are the same amp,but with smaller satellite speakers,ideal for placing on different stands or wall mounting.
the IS100 is a sub/amp with tiny golf ball speakers,which are essentially tweeters only, so subwoofer placement is essential(basically a system for people who want speakers to be as invisible as possible,like the ladies!

)
as for the differences, check each thread, and also really have a look at sony's website, for pictorial difference to each.
to compare each sonically though, would require someone to have or have had both, and even then the view might be subjective.