The activity data and achievements displayed in your feed may be slightly different from activity to activity depending on the activity type and the activity itself. Please be aware that there is no way to customize the stats or achievements associated with your activity feed entry.
Strava highlights the more notable stats for each activity. For example, for a running activity, the elevation will appear in place of pace/speed if the elevation gain is greater than 100ft per mile. Otherwise, pace/speed will be visible on the feed. The information you see may also be dependent on the length of the text. For example, if you are not seeing elevation or pace but an empty space this may be because the time and distance take up more room on the screen, and therefore the next set of data (elevation or pace) is not displayed since there is limited room.
Strava may also include a banner with a single achievement in the feed entry. These banners may be displayed for your longest activity, challenge progress or completion, running estimated best efforts or a segment effort achievement. Activities that achieve a personal record or a top 10 segment effort for run activities will display an achievement banner in the mobile feed as well as on the activity detail page.