This is a "depends" answer. First, the simple answer: is brighter/lighter. Typically when the size of the color increases (like from a small chip to a wall), then more color comes out and it appears brighter. In reality though, the way a color ultimately appears depends on many factors, the main ones being the lighting and the colors surrounding it.

First, color is completely dependent on the light source in the room. Sunlight tends to wash out colors leaving them look a bit duller. Incandescent lighting tends to leave colors looking warmer and brighter while fluorescent lighting (depending on the bulbs) may leave it a bit duller.

The second biggest factor affecting how a color looks is the environment and the surrounding colors. For example, if the carpeting is a very dark color, then even a medium tone color may look “too light” when viewed next to this darker color. Similarly, if your carpeting is an off white, then same exact color may look “too dark”. It's kind of like eating a chocolate donut and drinking coffee. Your coffee tastes sweet until you take a bite of your donut, and then your coffee isn't so sweet anymore.

The existing wall color plays a huge role when sampling your colors or beginning the painting project. Once you start painting you may not like the way the color looks because the existing wall color is messing with your perception, but once the wall is completely painted the color looks great.

Keep in mind also that as paint dries is darkens. When you first start painting the wet paint will look much lighter and brighter than it will once it dries.

Hope this helps!

P.S. this article may be helpful: http://www.myperfectcolor.com/blog/how-to-sample-paint-colors/

Thanks for the prompt response! Your explanations have proven helpful indeed. Off to get samples and slap them on the wall to see...

you can get your samples online here! :)
you'll get them fast.