What is the difference between a marketing plan and a marketing strategy?

I had a little discussion with a colleague and we could not agree on the definition of each term (marketing plan / marketing strategy) and the key differences between the two words.
Also, is the marketing strategy part of the marketing plan or the other way around?
Thanks

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).