Rounded corners are easier on the eyes, because they take less cognitive effort to visually process.
Scientific research done on corners by the Barrow Neurological Institute found that the “perceived salience of a corner varies linearly with the angle of the corner. Sharp angles generated stronger illusory salience than shallow angles” .
Rounded corners also make effective content containers. This is because the rounded corners point inward towards the center of the rectangle. This puts the focus on the contents inside the rectangle. It also makes it easy to see which side belongs to which rectangle when two rectangles are next to each other.
If you want to read more: http://uxmovement.com/thinking/why-rounded-corners-are-easier-on-the-eyes/
But of course its also brand dependent, but styleguides can be modified and print and web is not the same..