Hi,
the main difference is, Spybot 2.1 have a Anti-Virus-Engime (Home-Edition or above). But Spybot 2.1 aslo have a number of other new features and fixes.
An overview about the new functions of Spybot 2.1, you can find here: http://www.safer-networking.org/2013...-2-1-released/
If you dont need a Anti-Virus or already have one, you can download the new Version of Spybot, absolutly free, directly from here: http://www.safer-networking.org/mirrors/
If you like to order a licence for the Home or another Version, which includes the AV-Engime, click here: https://www.safer-networking.org/private/purchase/