Both code does the same job:
ColoredBox(
color: Colors.blue,
child: SizedBox.fromSize(size: Size.fromRadius(100)),
)
And
Container(
color: Colors.blue,
child: SizedBox.fromSize(size: Size.fromRadius(100)),
)
So, what's the benefit of using ColoredBox when it only supports just one property color which is also provided by Container?
Looks like this has now changed according to this post:
https://flutter.dev/docs/release/breaking-changes/container-color
So actually just specifying only the color property in a Container would be optimised under the hood to ColoredBox by default now.
Unless I'm reading it wrong?
Your 2nd code
Container(color: Colors.blue, child: ...)
results in a widget hierarchy that uses a BoxDecoration to paint the background color.
BoxDecoration also covers many cases other than just painting a background color and hence it isn't as efficient as ColoredBox widget, which only paints a background color.
TL;DR:
If your use case is to only provide a background color, go for ColoredBox and not a Container.