You may notice that your activity stream shows more information when viewed on your desktop versus when viewed using the HubSpot mobile app on iOS or Android.
On mobile, only sales email activities are shown in your activity feed, such as email sends and opens. Other activites, such as lead revisits and sales document views, won't be shown.
Here is an example of what your activity stream would look like on your Android device:
And on your iOS device:
And here's what your activity stream would look like on your desktop, which includes sales email information in addition to other sales activities such as sales document views and lead revisits (if enabled):