To me, the biggest difference between these two episodes is the outcome and what it tells us about the societies. The Salem Witch Trials ended up in people being convicted and executed. The Chicago 7 trial ended up with all the defendants being acquitted.
What this tells us is that the earlier episode occurred in a society that did not really care much about the legal rights of the accused. Once people were accused, they were more or less convicted.
By contrast, the Chicago 7 were acquitted even though they were very disagreeable people. They abused the judge and the whole legal process but yet they were aquitted, not convicted based on evidence. This shows a society that values the rule of law.