The difference may be its Warranty Level and browser trust. A Domain validated certificate is available at cheap price, but EV SSL certificate is available at higher than DV. But, EV offers green address bar, padlock and trust site seal so it expensive than a DV SSL.
But, if you want secure your blog only than Domain validated certificate like positive ssl, essential ssl or comodo ssl are the best option that is available cheap price at https://comodosslstore.com
Comodo is cheapest CA now and provide highest web security. 256 bit encryption, unlimited reissue, unlimited server license and best support.
Try https://comodosslstore.com/ to find best ssl deals.
You can get SSL Certificate from https://comodosslstore.com/
Its offer different types of SSL like Domain validated, organization validated, extended validation ssl certificate at affordable.
If you can have wildcard or multiple domain security with unlimited re-issue and unlimited server license.
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For ecommerce site you may get better SSL Security solution at Comodo SSL Store at low cost with highest security....
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Hope you will get better solution here..