When you worked with flutter you might have noticed that some widget uses MaterialColor and some users Color as the value type. What is the difference between those?

The one place where I found MaterialColor is in the ThemeData. In ThemeData we can set the overall color scheme of the application. There are nearly thirty different color values that we can set. Every argument is excepting a Color value but one, primarySwatch, is excepting MaterialColor. So, what is the difference between these two?

Let's describe the easiest first. As I said, everything other than primarySwatch is expecting a Color as the value. Color is nothing but a defined color value. When you use Colors.green and not specifying the opacity number for the argument then it's basically passing Colors.green.500. So, the argument is getting a single color value.

Now, in the case of primarySwatch it is excepting a swatch of colors, or in other words a group of Material Colors. Here you cannot use Colors.green.500 because then we are passing one single color as a value. Instead, we need to pass Colors.green which represents the swatch of colors. With this color value flutter sets the overall color configurations of the app. The system bar will be set with 700 of the color selected and the app bar with 500 of the color selected. And many other sections too will be having a similar color scheme.

Black And White
You cannot use Colors.black and Colors.white as the values for primarySwatch because the two don't have a swatch of colors. Instead, they are individual colors identified with the opacity level. If you look at this link you can see that black and white don't have color variations starting from 50 to 900. They both have only 7 colors defined by opacity.

Even though you cannot use Colors.black and Colors.white as values to primarySwatch you can use the same for other color theme options. For eg: you can set the primaryColor: Colors.black which then have almost the same effect that you where expecting with primarySwatch: Colors.black