The original Zouaves were made by Remington during the Civil War but were put into storage and never issued. (That's why Zouaves are frowned on at reenactments and at the N-SSA.) After the Civil War, they were sold as surplus, and many were converted into farm shotguns, etc. Surviving unaltered specimens were often found in excellent condition. Because of this, some excellent examples were sent to Italy and formed the basis for the first long-gun Civil War-era reproductions. These were popular at reenactments in the 1960's and 70's, until word got around about their non-use during the Civil War. Now, Zouaves are considered the height of "farbiness" at such events.
This is certainly not true of Mississippi rifles, which saw wide use in the Civil War. If you have a choice between a Mississippi and a Zouave, go with the Mississippi. Also, go with an early Zoli Mississippi reproduction rather than a later Euroams one. The early repros had a one-piece barrel with a standard breechplug, while the more recent ones had the breech end (including the bolster) cast as a separate piece and then joined to the rest of the barrel. The seam is clearly visible ahead of the bolster.
) I can see the differences between the two rifles quite clearly. 
