What is the main difference in a Secured Form?

2.Also there is an option of Embed Form -> Source -> Secure Form. What is the main difference of having it checked against unchecked?

The main difference in the between them is that the Secure Form box ticked makes a Secured Form (SSL Submissions) which uses a high encryption level whereas if the box is unticked it is a Standard Form (Standard Submissions) and it is not encrypted with the exception of the payment gateway for payment integrations. 

Very helpful, thanks Kade.

Hi again, I'm not sure if you'd be interested in this or not but I just wanted to let you know that we've now released a new feature for creating Encrypted Forms earlier this afternoon.

You can find out more about this here http://www.jotform.com/encrypted-forms/ which may or may not be of use to you as it offers another way to secure your forms. :)

Thats a nice option, ill keep that in mind. 

Would be nice that the encryption can be added to existing forms. I will launch without the encrypted forms because I would like to be able to manipulate mysql data for now.