What do the two different icons between a contact’s avatar and name mean?

There are two different icons between a contact's avatar and name, the phone handset icon and the SatPaq icon. 

Messages sent to a recipient’s cell phone number are displayed with a phone handset icon.

Messages sent to a recipient’s SatPaq Username are displayed with a SatPaq icon.

Messages can be sent directly from one SatPaq to a second SatPaq. This is useful when both people are out of cell range.  In this case you must use a person’s SatPaq Username to send directly to their SatPaq.