Well, ....his posture, expression and position are pretty good clues. The posture is one of 'control' and his expression is 'all business'. He's running the show.
Now, take our grey haired friend in the back, ....he's caught in a candid position and doesn't correct his posture in any way for the picture (which they clearly know is coming) to project any particular authority, .....why would he? ...so he naturally just projects friendliness. So, if I was a beting man, .....and I am (lol) our man on the left is, .....'the man'.
While we're at it, .....our Leo's posture reads to me, .......dilligence.
.....and I'll take a stab with our young friend and call him out as an intern. Deer in the headlights comes to mind.

.....but it remains, ....just a guess and of course I could be wrong.
