- Moderated P: This represents that you will be asked to put your information, some of which are mandatory but all of which is scope-adjustable. You can set your 'circle-of-trust' to whom you want to expose which of your data (just me, friends, friends-of-friends, everyone or some other representation). Your choice to hide the details you don't want to reveal, will be respected.
- The Open P: In this case, you don't have any permission to change the scope of the information that you upload. Your data 'may be' accessible throughout the web publicly; 'may not be' as well, depending upon the companies' policy and structure - but the security of your information is completely on their hand. Even if the company wouldn't sell-out your data, it has a fair chance to passively help the spammers/stalkers. So, the icon tells you here, if you want something to be secret, don't tell it in these situations.
Some web-services/applications may need some of your details, some require very handful things and for some you have to literally digitize from entire of your music choice to appetite preference. Let's think of a discussion forum which 'need' only your email ID to identify/contact you, but 'offers' to fill in a profile "if you'd like to", which will be visible by all other members/visitors/web alike, then it's significantly different from some other web-service, where it asks your details to fill in and gives you the choice to maneuver it's exposure.
So, this is about most of it for the privacy-icon designing. Now we have to consider the abuses & exceptions.