Louisiana Voodoo, a.k.a. New Orleans Voodoo, is a tradition or practice originally native to Louisiana but has also spread to other locations due to the spread of books, media, and the Internet.
The practice of Hoodoo is only a minimal component of Louisiana Voodoo. In days gone by, Hoodoo played a more prominent role but Louisiana Voodoo has now slowly evolved into an "anything goes" tradition where practitioners can worship whatever god or goddess they so choose, and much like Wiccans and New-Agers, heavily borrow as they seem fit from other religions. A more proper description is that the practice is highly eclectic in nature.
With regards to the practice of magic, some remnants of Hoodoo can be found in the practice of Louisiana Voodoo. The two practices are alike in the use of candles, baths, and the working with Saints. An example of a small difference between the two would be that Louisiana Voodoo practitioners refer to a mojo as a "gris-gris". The main differences between the two is that there is a predominance of creative magic, magic devoid of an established lore, and differing uses for items found in Louisiana Voodoo compared to Hoodoo. Probably the most obvious difference between the magic of Hoodoo and Louisiana Voodoo is that practitioners of the latter will invoke or call upon pagan gods or spirits while Hoodoo practitioners, being Christians, frown on such. Both traditions honor the Saints, use Christian emblems such as the cross or crucifix, holy water, and venerate the ancestors.
Louisiana Voodoo should not be confused with Haitian Voodou. The two are completely distinct.
Practitioners of Louisiana Voodoo tend to be people who seek a more wider spiritual path than the Christianity of traditional Hoodoo.
Note: To confuse matters further, there are actual Voodou practitioners in N.O. and Louisiana. There are also members of other African Traditional Religions, such as Palo, Santeria, and IFA. These peoples should not be confused for practitioners of Louisiana Voodoo unless they claim to practice Hoodoo. Confused?