Avira Internet Security upgrades some components of Avira Free Security to their Pro equivalents, but others still require separate purchase, and many typical suite components are absent. It’s just not a big improvement over the free suite.
Avira Antivirus Pro offers the same basic protection as Avira Free Security, plus a few added features that don't all work well. Stick with the free edition or, in a business setting, make a better and less expensive choice.
Heimdal Next-Gen Antivirus Home scans for malware on demand, on access, and on schedule, but it lacks protection against dangerous and fraudulent websites.
Heimdal Threat Prevention Home fends off dangerous and fraudulent websites as well as direct online attacks, but it omits the antivirus basics that consumers expect.