There is not very much difference between speak and talk. Talk is the more usual word to refer to conversational exchanges and informal communication. ***When she walked into the room everybody stopped talking.*** Speak is often used for one-way communication and for exchanges in more serious or formal situations; the usual word to refer to knowledge and use of languages. ***After she had finished reading the letter, nobody spoke.*** ***She speaks three languages fluently.*** Did this help you?

For example: What languages do you speak ? Can we talk for a muint ? --- He's speaking rubbish ! I talked to her about this problem. I do not know when or where or even why you should use "speak" or "talk" but you could know this by the sound of the phrase, it could tell you whether it's right or wrong.

In a nutshell: To speak is to say words with your mouth. Speaking may not be directed at anyone in particular. You can speak to a wall if you like. To talk is to carry on a conversation. Talking is usually directed at someone, but you could talk to yourself if desired.

The question was answered well but I want to add to it using Spanish verbs. I would think about it more like hablar and Decir. That is probably the closest words in comparison to English and Spanish. Thinking about the differences of those words would be the same as speak and talk

SPEAK WHEN A PERSON IS ADDRESSING EXAMPLE JON WILL SPEAK AT THE CONFERENCE ON MONDAY. WHEN YOU HAVE EXPERTY IN A LANGUAGE EXAMPLE JACK SPEAKS ENGLISH. IN A FORMAL WAY MY BOSS SPOKE TO ME ABOUT MY PERFORMANCE. TALK WHEN TALKING ABOUT THE SUBJECT OF CONVERSATION. EXAMPLE WE TALKED ABOUT OUR CHILDHOOD DAYS. FOR FRIEND OR CHAT EXAMPLE HE TALKED TO JIM LAST NIGHT. EXAMPLE DO NOT TALK NONSENSE.