Facebook for me is just an address book of all my contacts. I never share anything personal there due to the number of privacy settings I need to hop through to make sure I shared with the right people.

Path is just a curated set of close friends with whom I feel free to share anything. Also when it came out Path mobile app is far better than Facebook.

I use Path (mostly) for pictures of my kids. Path is invite/opt-in which makes it easy to share with only the family and friends who are interested.

I don't want everyone on Facebook seeing my family photos any more than they want to be flooded with updates from a doting father.