Grid spanning vs grid item size changing

Hello forumers,

I’m going through the CSS: grid lesson and basically I’m wondering the differences between “explicitly” defining the grid and whatever the alternative would be called.

whatever not explicitly would be called:

grid-template: 1fr 2fr 1fr / 1fr 1fr 1fr /*the grid items are sized differently*/


grid-template: repeat(4, 1fr) / repeat(3, 1fr); /*grid items are uniform size*/
grid-row: 2 / span 2; /*middle row is taking up two grid items*/

At least visually, these grids should be the same; 3x3, with the middle row twice as big as the top and bottom.

Am I wrong? What is happening here? Is this implicit vs explicit grid?