‘Explain Social Media Tools in Simple English’ could be exactly what you are looking for if sometimes other explanations get too complex.
A few analogies came across my computer today that I thought might help you to get an idea of the most commonly used tools are.
From Lets Get Social:
From an article that untangles Social Media concepts :
LinkedIn – an online Chamber of Commerce, Trade Show, or place where business people meet.
Twitter – Party or Dance
Facebook – Potluck/Picnic/Backyard Barbecue
Youtube – Your own free TV Shown or Channel
What ways have you heard Social Media described in simple terms?