Abelleh:
If you were a uniformed officer in the military and you ran into another uniformed officer, you could immediately start conversing with him about military and geopolitical matters. OTOH, if another person in street clothes walked up to you and started talking to you about military matters, you would rightfully respond to him as if he was unsophisticated in military matters. If you realized in mid-conversation he was an officer too, you would change the perspective and nature of your conversation.
Much the same as you described your experience above.