Almost 60% of the Veneto lies in the valley of the Po River. The lower plain of the Valley is incredibly rich in both arable, fertile land, and water. It is one of the most important agricultural centers of Italy, producing wheat, maize, fruits, and the related wines for which the region is rightly celebrated. (Of course, until it was reclaimed by the Romans, a good portion of this area was a useless swamp, but that's another story.) The Adriatic coastline is also, unlike that of the northern Tyrennhian Sea, very rich in fish, as are its many rivers (fish farming). In addition, it produces hydro-electric power.
Despite all these natural resources, it has not always been very prosperous. That is a very recent phenomenon, really, post 1970 or so, after centuries of alternate periods of decline and stagnation of the Venetian Republic. Part of this, in my opinion, is attributable, during that period of decline of the Venetian Republic, to the misrule of its oligarchic, feudalistic government, which remained in control until 1797, when it was invaded by Napoleon. It then became part of the Austro-Hungarian Empire after the Treaty of Vienna. Although it had earlier petitioned to form an Italian union with the territories already under the control of the House of Savoy, it didn't become a part of The Kingdom of Italy until after a referendum was held. The vote for unification was virtually 100%. (I would be wary of any Wiki articles on the subject. Much of the content consists of highly editorialized commentary, bereft of documentation, by someone who appears to me to be a typical Liga Veneta supporter. The Liga Veneta was a founding party of Lega Nord.)
As a result, in a region which today is home to around 5 million people, about 3 million were forced to emigrate between the 1860's and the 1960's.
There are three main areas of economic prosperity in the region in my view; its agricultural sector, the petrochemical industries right outside Venice, which have created the horrific pollution which has defaced this wonder of the world and is causing it to sink, and the many small and medium sized businesses producing things like eyeglasses and jewelry and foot and boot wear and clothing etc. (All of the latter, ironically, to my way of thinking, depend for their success to a large extent on the "Made in Italy" branding. I somehow don't think Made In The Veneto will quite do the trick.)
By way of comparison, the northwest (which doesn't have those agricultural resources, by the way) industrialized earlier, and is home to the kinds of large industries (automotive, in the case of Torino) which are experiencing so many problems throughout the developed world. The kind of family owned, or at least small and medium sized industries of the Veneto, (there are no large cities in the Veneto, and no large factories) and my father's Emilia Romagna for that matter, and increasingly, I hope, Toscana, are less affected by the types of problems plaguing large industries. (Just in terms of costs, for example, you need a whole lot of very expensive, imported energy and raw materials to make cars...Italy has no coal or gas or oil of its own, and no iron for that matter...absolutely everything has to be imported.)
As to Liguria, it has next to no arable, fertile land, no rainfall in the summer and floods in the winter, its eastern end is prone to earthquakes, and it hasn't had any exploitable minerals since the Copper Age. Oh, and no large navigable rivers, and no opportunity to create hydroelectric power, and no fish in the sea or timber on the mountains to quote the old adage. A grim place to make a living, even if it's breathtakingly beautiful. It has always relied on the sea (the control of trade with the east in the Middle Ages and Renaissance), its ports, and banking, more recently with some flower farming, and tourism, but it has never been easy.
There are other confounding factors in Campania unfortunately. Still, you can see the difference between it and regions like Calabria, for example, which has virtually no flat, arable land, no major rivers, inadequate rainfall, and no other natural resources. Sicily once had good land, but the last rulers to manage its resources properly, in my opinion, were the Saracens.
There, doubltess more than you really wanted to know...