Since the javelin can hit air targets when they are soflam, can the stringer hit ground targets that are soflam? And if so do you need line of sight to lock onto the ground vehicle?
The stinger is described only as a surface to air weapon, and it operates as a heat-seaking missile used to take out enemy air units, fighter jets, helicopters and UAVs.
Whereas it is stated explicitly in the Javelin page that it can be used on any soflam'd target, making it useful in taking out both air and ground units alike. The Javelin works by laser designation, not heat.
There is even a paragraph in the multiplayer section of the Javelin page that describes the tactics of using a SOFLAM and a javelin to effectively take out air units, so I would say that this is definitely a feature exclusive to the Javelin.