Differentiate between cupcake & muffin

Distributed some of my cupcakes to some friends. Then there came a confusion of it being a muffin or a cupcake. Of course, i knew it was a cupcake since i was the one who made it. But how does one on the receiving end knows whether its a cupcake or muffin?

Decided to look it up and promised Ying that I will keep her informed once I do. So for the benefits for all, the difference is as follows:

Cupcake:

• a small cake designed to serve one person, usually made in a small paper cup container.
• Usually decorated with frostings and sprinkles.
• A simple cupcake uses the same ingredients as most other standard cakes - incorporating butter, sugar, eggs, and flour.

Muffin:

• A muffin is a bread- or cake-like baked good. It resembles a cupcake
• Muffins have cylindrical bases, rounded conical tops, and are usually sweet.
• there also exist savory varieties (such as cornbread muffins).
• muffins often have a "topping" baked in, such as blueberries or chocolate chips.

I think my way to differentiate them is that muffin is more like inbetween bread and cake and will have thicker consistency. Usually, with loads of stuffs contained within them and cupcake is just like cake but miniature version, put in a cup! haha!!

Once again i got help from wikipedia:
http://en.wikipedia.org/wiki/Cupcake
http://simple.wikipedia.org/wiki/Muffin