What difference between SharePoint Web parts and user controls?

Usercontrol:
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1. User Controls are like you are creating your own functionality though grouping up the Asp.net controls.
2. Can not be used on any general SharePoint page.You gotta code a custom page layout and embed the usercontrols.
3. Do not have the ability to communicate/connect to other user controls on the same page.

 

Webpart:

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1. Web part are the one that are personizable.

2. can use on any page through out.
3. webparts can communicate/connect to other webparts and make use of the master/detail.
4. webparts are like usercontrols are added in code but wedparts are added at runtime.

 

Do you have any ideas? /Or yo can leave a message. (* ^__ ^ *)