Talk and speak

Talk and Speak refer to the act of oral communication and are used in the following types of situations:
1.Talk or speak - to somesone (about something or someone):
I talked to her today.
He spoke to Mrs.Perkins this morning.
He talked to us about the present-day economic system.
If I were you, I would speak to Mr.Green about the situation.

2. Talk or Speak -about something or someone:
After the lecture,some of the studensts stayed and talked about what the professor had said.
The lecturer spoke about the seriousness of juvenile delingquency throughout the world.
We talked about our old school friends all afternoon.

*Although both Talk and Speak are used in these constructions,we tend to use Talk referring to discussion or coversation on a more informal level, as in the sentence,""We talked about (rather than spoke about) our friends." Also compare:
We talked for an hour.(Our conversation lasted an hour)
He spoke for twenty minutes.(His speech lasted twenty minutes.)

3.Speak is ordinarily used to refer to the act of making or giving a speech or to the manner in which someone speaks.
The President will speak at the banquet.
Did the football coach speak at the rally?
You speak very clearly.
Mrs.Neeley speaks French with a Texal drawl.