The Industrial Revolution describes a period of time with many advances in technology, particularly in the mechanization of agriculture, factory production, and energy supply. The Industrial Revolution may be described as having occurred in two waves- the First Industrial Revolution, from about 1760 to 1840, and the Second, from about 1870 to 1914. In between the First and Second Revolutions, there was a lull in innovation but an increasing spread of the technologies developed during the First.
Perhaps the most notable similarities (or largest theme) of the First and Second Industrial Revolutions were the increases in differentiation of labor and centralization of production. Before the Industrial Revolutions, labor and production were largely on a homestead or estate basis. The production of food, textiles, and other goods was mostly done on a small scale by a household for their household. Trade did occur, but was not the main means of acquisition of the goods a household needed. During and after the Revolution, there was a trend towards increasing differentiation of labor, whereby someone may perform just one role in the complex production of goods. An increase in differentiation of labor contributed to an increase in centralization, where lots of raw materials may be transported to one place, transformed into a high quantity of finish goods, and transported elsewhere for sale.
Let's consider the example of the textiles industry to better understand these trends. Before the Industrial Revolution, the production of cloth was mostly performed by one or a few persons in a household, and they only made enough cloth to suit their needs. A person would have had to harvest wool or flax, comb or thresh the fibers to make them usable, spin it into thread, weave the fabric, and then dye or ornament it if desired. This process, performed within one household, was very labor intensive and time consuming. The invention of machines which could perform functions like preparing fibers for use, spinning of thread, and weaving, dramatically cut own on human effort and enabled the production of a higher volume of cloth in a comparable amount of time. By differentiating labor and designating more specific jobs to workers (like harvesting fibers or manning a weaving loom,) production rates increased significantly.
Another similarity between the First and Second Industrial Revolutions was a general increase in quality of life. Labor was not so back-breaking as it was before the Revolution, increasing use of electricity, and expedition of travel and transport contributed to a better quality of life. That being said, some types of labor (like factory work) were quite dirty and often caused health problems for the workers. During the 19th century, wages of workers significantly increased, but they still could not often afford the very goods they were producing. Differentiation of labor enabled an increase in leisure time and the prospect of education. Throughout much of Europe and the United States, a new middle-class developed thanks to a general decrease in the amount of time spent laboring in production of goods.
In addition to the increase in differentiation of labor and centralization of production, the Industrial Revolution influenced massive population growth and increase in Gross Domestic Product.