A lot of work has looked at this, and in general researchers think it’s very similar mechanisms that underlie different addictions. The causes can vary a lot though, not just between substances but from person to person. For some people their addiction can stem from a traumatic moment and they use it as a coping mechanism, while others are at risk to become addicted due to their genetics. Hope that answers your question 🙂
This is a very interesting question! A lot of people argue that obesity may be due to food addiction so there has been lots of research into which areas of the brain are activated when we eat. Some people argue that because the reward circuits in the brain that are activated when we eat foods high in fat and sugar are the same as those that are activated with alcohol or some drugs that high fat/sugar foods are addictive. However I think it’s more complicated than that, after all not everyone that drinks alcohol becomes addicted to it in the same way that not everyone who eats foods high in fat and sugar is obese. There are probably many other factors that influence addiction such as someones early life experiences etc.