As adjectives the difference between stylish and fashionable is that stylish is having elegance or taste or refinement in manners or dress while fashionable is characteristic of or influenced by a current popular trend or style.

They are basically the same thing. "Fashion" is the overall concept of how clothes look and what is popular. "Style" is both a single design of clothes ("I'm not sure about the style of that outfit....") and the overall ability to have good judgement in clothes ("you have great style!"). The second is more of a slang way to use it, but it is so widespread that I don't think that anyone even remembers that it used to be slang. So, as an extension, stylish might refer to a single outfit (but could easily be used as a way to describe someone). Fashionable might be used more to describe a person's capability to dress in a popular way (but could be used to describe a single outfit). As you can see they are almost identical and could be used interchangeably. In fact, in my dictionary, they are both in the definition of the other. Don't worry too much about which one you use. I don't think there are many times that you could be wrong in using either one. The complexity of this answer should show why no one had answered you yet.

Hi Maki! The words can sometimes be used interchangeably but the subtle difference between the two is basically this: “Stylish” generally refers to someone’s opinion that the artistic choice of clothing is attractive looking. Versus “Fashionable” generally refers to the opinion of most people that the artistic choice of the clothing is popular in the current time period and in that particular area and culture. Both “Stylish” and “Fashionable” can describe many types of decorative items. For clothing it can be about as few as a single piece of clothing or even a complete outfit. These words can also describe design or artistic choice of things like furniture or a car. I hope that helps! -Caitlin