Your question about the differences between using a preferment versus a long-fermented dough is a good one. Unfortunately, there is no simple or easy answer to that question. To give you an example, a poolish that is classically made comprises only flour, water and commercial yeast. The flour and water are used in equal weights, and the amounts of yeast are usually fairly small. For example, for a classic poolish that uses water at 60 degrees F and is to be prefermented at a room temperature of 80-85 degrees F for about 3 hours, the yeast (IDY) is about 0.5% of the poolish flour. The corresponding values of yeast (again, IDY) for a prefermentation period of 7-8 hours is about 0.23% of the poolish flour, and for 12-15 hours it is 0.033% of the poolish flour. However, over time, people have dramatically altered the characteristics of what they often refer to as a "poolish". For example, people use different amounts of the poolish (some even change the ratios of flour and water), they drastically change the yeast quantities, they use different water temperatures and prefermentation temperatures and times, and they add other ingredients to the poolish. Some even refrigerate the poolish. Each combination will have its own different and unique effect on the dough (including its strength) and the finished crust characteristics, including the taste and flavor of the finished crust, and its color, texture and aroma. Depending on the particular form of the "poolish", and the amounts and types of acids and other byproducts produced, the flavor of the finished crust can be mild, pronounced, sweet or sour. Some of the flavors might even be considered objectionable.
I understand that there are some pizza operators who have used preferments in their dough making, although they are quite rare. On occasion, Tom Lehmann has suggested methods and dough formulations based on preferments. One example, for a "take-and-bake" dough, is described in Reply 362 at http://www.pizzamaking.com/forum/index.php/topic,576.msg23239/topicseen.html#msg23239
. Tom has also discussed what he calls a "sponge" preferment application at the PMQ Think Tank at http://thinktank.pmq.com/viewtopic.php?p=38304#38304
. I actually used the latter "sponge" method in connection with my interpretation of JerryMac's NY style dough recipe and reported on the results at Reply 28 at http://www.pizzamaking.com/forum/index.php/topic,6515.msg62814.html#msg62814
. I think most commercial pizza operators stay away from using preferments because of the complexity and time involved in preparing and managing them. Also, most pizza operators use low-cost help to make the dough for their operations, so considerable training would be required, much of which would be wasted because of high labor turnover in pizza operations. Where you are more likely to see use of preferments is by artisan bread makers. They understand the biochemistry of dough much better than others and they also plan the use of their preferments by including special temperature and humidity controlled rooms for preparing and maintaining their preferments.
I personally am a big fan of using preferments. I like the flavors that they impart to the finished crusts. I have been able to get comparable (and sometimes even better) crust flavors from a long, cold fermentation, but it takes a dough with more than just a few days of cold fermentation. It will usually take from six to fifteen or more days of cold fermentation.
If preferments intrigue you, you might want to take a look at the following threads: http://www.pizzamaking.com/forum/index.php/topic,5851.msg49940.html#msg49940