Actually the columns on the rows are indeed equal height. If you refer to the height of the element with the orange border, then just put the orange border on the parent element so it takes the whole height. Check out this screenshot I took – you can see both columns in the code and the left one is selected showing its real height that it’s as much as the other column.
These websites don’t seem to be hosted by WordPress.com, instead they are using the WordPress.org software on your own server (self-hosted). This forum is for providing support only for websites hosted on WordPress.com and if you need help here for a website hosted by WordPress.com please create a new thread.
There are two versions of WordPress – WordPress.com and WordPress.org. You can find more information about the differences between them here.
I would suggest that you look at the support page of WordPress.org and their forum – https://wordpress.org/support/. If you don’t have an account there you can create one for free here.