“Sprechen von” vs. “sprechen über”

Question

I’m not very far into learning German, so I’m still extremely sketchy on prepositions.

I thought über was more in line with a physical location than a concept, but then I’ve seen phrases like Ich spreche use both von and über seemingly interchangeably to denote the topic of speaking.

Are these saying entirely different things, or do they mean the same thing with different connotation, or is there no real difference? And if there is a difference, then under what circumstances should each be used?

Answer 1

Wow, this one is hard.
A very good idea is distinguishing between topics and people (like Kilian did). Maybe some more examples will help.

You usually talk about a topic and generalize it to some point. The German "über" does the same just like in "Übersicht". You ask somebody to tell you about something to get an impression. When I tell you something about a topic I am giving you more like a summary so you get the idea.

What is he talking about? - Worüber spricht er? (Umgangssprachlich auch: Über was spricht er?)
(He is talking about nature (in general)).

When I talk of a certain topic I (maybe) want to convince/win you. I think the contents are more important here.

He is talking of nature and its different animals. - Er redet von der Natur und den verschiednen Tieren.
(Ending the sentence after "nature" in both languages feels odd because you expect something else to follow. At least I do.)

To sum up:

Did he tell you about something? - is generally asking (über).
Did you hear of this thing? - is going further into detail (von).

Some special case might be:

Someone is talking well of you. (von, detail: talking well)
Someone is talking about you (über, in general, no judging)

Speaking of "of" and "about", I'm about to go off (so much confusion :D)

Answer 2

No two constructions are ever exactly equivalent, but as a native speaker I feel that "reden von" and "reden über" are pretty close to indistinguishable.

One slight trend that I can see is when talking of people. "Reden über" tends to be used in a judgmental way. For instance, "It's not nice to talk about other people when they are absent" would more often use "über"; "reden von" tends to be used neutrally when clarifying a reference: "Did you mean me? - No, I was talking about Robert."

Edit I can see now that there is a similar distinction with talking about topics.

"This week's presentation will be from the biochemistry department, and Dr. Maynard will be talking about enzymes." -> "über"

But:

"What does Dr. Maynard mean with the 'current political relevance'?" - "He was talking about AIDS." -> "Er spricht von AIDS."

One construction simply lists a topic; the other clarifies a specific reference.

Answer 3

Über is imho a better choice for a non native speaker since mapping von to from and über to about saves some decisionmaking ie. mental energy when producing L2.

Answer 4

An example one might think outdated but is seemingly not, from the early 19th century German; The song "Gute Nacht" in Schubert's cycle "Winterreise" (written 1823, composed 1827) contains the following verses:

Das Mädchen sprach von Liebe,
Die Mutter gar von Eh'

Listening to the whole song, you will know that the young woman and her mother weren't just talking about love and marriage in general.