Below are the definitions of the "Last Contacted" and "Last Activity Date" contact properties:
Last Activity Date - The last time a note, call, email, meeting, or task was logged for a contact. This is set automatically by HubSpot based on user actions in the contact record. Last Activity Date is based on when the activity was entered into HubSpot.
Last Contacted - The last time a call, email, or meeting was logged for a contact. This is set automatically by HubSpot based on user actions in the contact record. Last Contacted is based on when the event actually took place.
Example 1: If you log a call that took place yesterday, the Last Activity Date will point to now, and Last Contacted will be set to yesterday.
Example 2: If you schedule a meeting for tomorrow, Last Activity Date will point to now, but Last Contacted will not be updated until the meeting takes place, at which point Last Contacted will take on the timestamp of the meeting.
Another key difference between these two contact properties is that the Last Contacted contact property would only update for calls, emails, or meetings and not for a note or task.