Often these terms are used synonymously to describe a soup but minestra and minestrone, zuppa and passato, crema and vellutata are not the same thing. The difference resides in ingredients, like pasta or cereals, and thickeners such as dairy products or fats. So you can start from the same vegetables and use them in each of these versions, making the final product either very light, like a passato or a minestra made only with green vegetables, or very rich and with a high nutritional value, so much so that it’s considered a complete meal.
Here is a small technical dictionary – often refuted by regional recipes which traditionally use different names.
Minestra
The minestra takes its name from minestrare, to serve, because it was served at the table by the head of the family. In addition to the usual vegetables, it contains cereals such as rice, pasta, farro, barley... The minestra is rather liquid, in Lombardy it’s prepared with the addition of rice, while in Veneto and in Emilia Romagna with pasta or cappelletti. Chinese noodles and Japanese ramen technically fall into the minestra category.
Zuppa (soup)
In addition to vegetables, zuppa never includes rice or pasta. It’s only served with croutons, at most. Its name is similar in all European languages and derives from the Gothic suppa, which indicated the slice of bread that was placed in the bowls before pouring the soup. Zuppa has a dense and substantial appearance, very little liquid is used, which gets absorbed by bread and croutons. Zuppa is widespread in Tuscany, with collard greens or kale as the main vegetable. In Calabria and Sicily it’s based on legumes and fava beans. In Sardinia it features bits of cheese.
Minestrone
A halfway point between zuppa and minestra, it was born after the discovery of the Americas, with the introduction of some fundamental ingredients like potatoes, corn and beans, which were previously unknown in the old world. Substantial and rich, a cereal or pasta can also be added to the minestrone, like in the classic legume version.
Passato
Passato is a vegetable soup, like a zuppa or a minestra, without pasta or legumes or cereals, which is blended at high speed. In the past a food mill was used and its consistency was determined by the type of mesh through which the vegetables were milled.
Vellutata
It is composed only of 2, maximum 3, types of vegetables like in the traditional combinations of potato-leek, zucchini-potato, carrot-potato. To bind the ingredients and give it a more appetizing and soft texture, at the end of cooking some cream or egg yolks are added.
Crema
It is preparation made with one main ingredient, pureed, and thickened with rice flour or milk. Rice crema, zucchini crema, bean crema for example.