Both Examples...

Column A is you, or the identification of the person you are emailing.

Column B indicates that this is indeed an email address.

Column C is the name of the company, internet service provider or who ever hosts your email.

Example 1

Column E is called a Top Level Domain (TLD). This is country specific, and in this example means a UK domain.

Column D is determined be the country the TLD represents, in this case the UK. They have determined that .co will represent a company.

So, as .co.uk domain will indicate a UK company. Generally only UK companies will have a .co.uk domain.

Example 2

Column D in this address is what is called a generic Top Level Domain (gTLD), which is not country specific. So a .com address could be an American company, a UK company or any other company in the world.