Yikes, this is one of those things that can make English a little confusing. They basically mean the same thing, but have a different feel to them. To speak is much more literal (and has a much more formal tone) - it means to communicate through speech, whereas to talk is much more conceptual (with a more casual tone) and usually implies a conversation or an exchange. Sometimes one verb is used over the other though: I speak English. We speak English. (very literal, referring to speech - one does not talk English). We talk to each other in English. (We converse in English, emphasis is more on the conversation) We speak to each other in English. (basically the same as above, but the emphasis is more on your speech and less on the conversation). We talked about our ideas in class today. (gives a sense that ideas were exchanged openly, as in a conversation) We spoke about our ideas in class today. (gives a sense that you presented your ideas to the class, more formal). Again, there are times where both verbs work, but they do convey different tones, sometimes the difference is very minute or can be unintended. I hope that this helps.

"Speak",emphasize language types or when the call way. As"talk",the content of the speech is attached.

I've been thinking about it and I don't think there is a difference. You could say "I spoke to him" or "I talked to him." .. Sometimes using "spoke" is more formal .. kind of like how "to chat" is more informal.