Free-Version Differences

I have been a long-time user of (and donated to) SB S&D 1.6.2 (Free). After visiting the website today, I understand now there are four versions available: 1) SB S&D 1.6.2 (Free); 2) SB 2.1 (Free); 3) Home Edition (Paid and Includes AV Protection); and 4) the Professional/Commercial Version for businesses (Paid). What is the "SB 2.1 (Free)" version and how does it differ from "SB S&D 1.6.2"?? If I choose to download SB 2.1 (Free), should I first uninstall SB S&D 1.6.2?

You could look at the comparison chart.It lists what Spybot 2.1 free version has and doesn't have.
http://www.safer-networking.org/private/compare/
Yes,you could uninstall Spybot 1.6.2 before downloading 2.1 if you want to.Spybot 2.1 should prompt you to uninstall 1.6.2,so you'd be a step ahead if you uninstall 1.6.2 first. :)