That's something that is not very well defined - for a common person at least. In many cases, there is a continuum between them, as there is between a dialect and a language. To me, an accent mainly consists of different sounds, whereas a dialect has a different sound, but also has many different words, and even slightly different grammatical structures. In my country, there are only a couple of different accents. In one area, people roll their 'r's, and that is called a Gore, or Southland accent. There are a lot of regional accents in Britain, and there is even a slightly different accent between the West and East coasts of the USA. For an example of an English dialect, the one I am familiar with is the Shetland Islands dialect. Although it is basically English, it also has a mix of Scottish, and Scandinavian words, and has a very strong accent. Would you like some sound clips to listen to?

What is the difference between accents and dialects? Accent is to do with only the SOUND of how you speak - the pronunciation of words, and also stress, intonation and rhythm. For example, the difference between the way most Americans, Australians and British people speak is simply a question of accent. We may sound different, but what we are saying is almost exactly the same. Native English speakers can almost always understand each other without any difficulty. Dialect is not only sounds, but also the WORDS and GRAMMAR which you use. People speaking different dialects may find it very difficult, or even impossible, to understand each other. For example, Arabic has many different dialects, and Arabic speakers from different regions may not necessarily be able to speak to each other using their local dialects. I hope this helps.