Once you have proved that the statement is in fact false, you have to prove that the other person said the false statement with the intent of causing you some form of harm. Slander and Libel. There are two different types of defamation of character. The first is when someone verbally says a false statement about you.
In William Shakespeare's Romeo and Juliet, Tybalt is the nephew of Lord Capulet and Juliet's older cousin. We can accurately describe the skilled swordsman as a tough, cocky and aggressive character who is always looking for a fight.
They could be completely different and one could be good, the other could be lousy. They're made to different specs and they're only manufactured by the same company. Just because SnapOn (who makes excellent tools) also makes Kobalt, doesn't mean Kobalt tools are as good as SnapOn. They're almost certainly not. There are dozens of manufacturers of flat-panel televisions but there are only three manufacturers of the panels themselves.