Q:

Grey vs Green padlock in address bar - technical difference

What is a technical difference between "grey padlock" and "green padlock" in URL bar in browsers?

As an example we can take:

Green padlock: Bank of America
Grey padlock: Google Search

Both of them are signed by proper CAs.
So my questions are:

What is a technical difference?
How does it impact my browsingsecurity?
Are there some best practises what shouldn't be done on pages with "grey padlock"?

A:

In Firefox, a grey padlock indicates that the site in question does not use an EV certificate. Sites using EV certificates shows up as a green padlock.
There is mostly no practical difference between the two types of certificates. Both are equally secure from a technical POV. For a more thorough answer about EV certificates, see What are the advantages of EV Certificate?

