The word "Talk" is used very much often than the word “speak,” To make a line of distinguishing between the two.; a major difference is that “speak” is used more in the case of formal occasions, and it is usually used by just a single person who is addressing some people or a group of them. While “Talk” does not require formal usage, so to say, and in most times, it brings an implication of dialogue between two or more people.
A good example is: “The manual workers started talking when the head of workers stopped speaking to them.” Another good example is: “He loves talking to his guests directly, but he does not like to speak in front of a large crowd.” A talker brings life to a conversation; he makes it very interesting while a good speaker would only do well when relating a discourse to a group of people together.