Most of these are just cosmetic locks to make users feel that they are missing many key features. I'm not a fan of this since it gives users a wrong impression. For example BD Free definitely detects PUPs despite what this setting page says. Out of the ones I see in the screenshot, Scan scripts is the only one that is not available in Bitdefender Free. Here by Scan scripts, it means AMSI scanner. BD Free doesn't have AMSI integration. Other core features that I can think of that BD Free does not have (not present in this screenshot) are memory scanning and command-line scanner. So, its behavior blocking component is indeed a bit weaker than the paid versions but for most things it's enough. Bitdefender's BB aka ATC is very powerful. Product updates are the same for BD Free and BD paid. There is no difference there. Bitdefender Free is the same thing as BD paid with some features removed. BD's setting file is human readable. I read that and it can be easily seen that in the free versions some things are disabled. I even tried replacing BD Free setting file with BD paid one. Hehe..but it resets itself to the default BD Free setting file.
Avast Free is more complete with all features. For Bitdefender there's also the thing of it writing about 400-800 MB data on disk on every signature update. Avast is much better at this with its brilliant streaming update mechanism.
In terms of overall protection, I think Bitdefender is a bit ahead of Avast but nothing significant to lose anyone's mind over it.
