I have a feeling that the $242, is for the Z5 model, which is less expensive.   They are both good guns.  
T/C says the only difference is that the Z5 has Williams sights on it and that the pull down actions pivot point is attached to a welded lug on the bottom of the omega barrels.  On the Z5 barrels the pivot peice is bolted on. 
But, I think the newer Z5's also have the Williams sights on them.  I was also told that the Z5 has a stainless breech cover, and the regular on doesn't, but I don't know if this is in fact true.