Verbs like "handeln", "reden", "sprechen", "erzählen" etc. can use the preposition "von" and "über" in an interchangeable way. I couldn't imagine an example, in which those two prepositions in a sentence with the above mentioned verbs lead to two different interpretations.
However I found this to be not completely correct and thus would like to discuss my understanding of German with others. Thus any constructive comment or answer is welcome.
I am inclined to proclaim, there is no difference at all. However, going by own feeling for language I ascribe "von" being more objective, creating distance between the speaker and the topic, potentially sounding more abstract, while "über" being more subjective, creating closeness between speaker the topic, sounding like he is somehow involved, affected by the matter.
An example like "Der Bericht handelt von..." contra "Der Bericht handelt über..." should make my point apparent. I find it clear that the former belongs more to a formal language, while the latter is rather narrative.
The question for me now, is, whether von generalize that point to the verbs mentioned in the beginning + possibly more verbs of that category.
Another two examples: "Der Politiker spricht von Menschenrechten." versus "Der Politiker spricht über Menschenrechte."
"Die Zeitung spricht von den Opfern" versus "Die Zeitung spricht über die Opfern."