Ah, right, I totally missed that you said Zoomed. Misscommunication at its finest

Now, I could be wrong, but from what I've understand, the difference is UV-lightning. The Exo-terra CLF bulb emitts a small amout of UVA (and no UVB). The walmart CFL bulb does not emitt UVA. However, the UVA is not really what's important for the plants, so the ordinary CFL bulb will work just as well (as long as it's the "daylight" one) (according to what other people have said, I've not used an ordinary one myself, just Exo-terra's).
Another aspect that raises the price alot is that the Exo-terra is a "special reptile product". Unfortunatly, this label make products expensive, even when it sometimes does not mean anything at all