I'm a little confused. What is the difference between Ally Occupied and Legion Ally Occupied? What does the number after Occupied mean? Ally Occupied planets show up as white shields whereas Legion Ally Occupied planets show up as enemy hostile.

Someone in your legion is either down or one of his friends is down.

Legion Ally Occupied represents an Enemy (not your friend) planet that is a friend of someone in your legion.

While you may not know the person you are attacking, they are allies with one or more people in your legion, and thus, you should think twice before attacking the planet. The number represents the people in your legion who are allied with this person. 43 is a large number - you might want to skip that one.

Think of it as. Legion occupy 43 = Facebook 43 mutual friends that plays Galaxy legion for the target planet owner
Example. Looking at player 1's planet in-game, 43 legion ally
Looking at player 1 in facebook, 43 mutual friends (assuming all mutual friends plays Galaxy Legion)

Thank you. That clears it up.