Whether you call it a "kitchen scale," a "food scale," a "brewing scale" or a plain old "coffee scale" the fact remains that a scale is a scale. These are all tools that measure that weight of objects. Almost all of them will have basic features like tare and be able to operate in grams or ounces. The differences between each scale type will come in the way of the more subtle differences between them. For example, a food scale might have a higher weight capacity and a lower resolution (say a 4000 gram capacity and a 1 gram resolution), while a coffee scale rarely needs to measure more than 2000g but will generally need 0.5 gram or 0.1 gram resolution. And then a kitchen scale might be more of a general use tool with a larger surface that can fit a big mixing bowl on it, where an espresso scale doesn't have to be very large at all. So, in summary: there is essentially no difference between the types of scales. They all serve the same function and they all work in place of one another. The scales only differentiate themselves by becoming more specialized and this tends to happen only as they get more expensive (a prime example being the Acaia Lunar, which is the best espresso scale, but really only works for espresso).