In both cases the additional "glance screen" information will disappear from the glance screen around 15 seconds after the glance screen has been activated (it's possible this might be a bug since this is also the approximate timing for glance's screen "peek" mode).
When choosing the "my text" option a settings button let you specify what the custom text should say and what text size (small, medium, or large) should be used. This option could be used to display your name (useful if there's more than one device of the same model in your family), or to display a message offering a reward / asking people to return your phone if it is lost.
When choosing the "lock screen notifications" option the detailed status notification information, as specified in the lockscreen Settings module is shown at the top of the screen. This can be customised to show information from any app that supports integration with this lockscreen notification functionality (e.g. Calendar, Twitter, Facebook, and many more).
Nokia has opted to use a large font to display this information, presumably in an effort to make the text easier to read from a distance, but this does limit the amount of information than can be displayed, as is demonstrated in the photo below. We would have preferred to see a small font size being used.
Windows Phone Store description:
See the time as well as useful notifications when your phone is on standby. Choose the Glance screen mode that suits you and enjoy the perfect balance of power consumption and visibility. Select night mode and your Glance screen automatically dims between the times you set. Download Glance screen and find it under Settings.
glance is a free download from the Windows Phone Store.