I know this seems rather obscure and can vary between people. A duke would obviously have more land and power than a baron, but when people refer to a noble's land as "estates" what do they mean by this? Did they own rural farming land mostly or control businesses in the cities? Or did they get their riches from trading and have foreign estates overseas? What was the general property they owned?
Estates would generally refer to all their holdings, specifically land holding. While they would inevitably hold some property in towns and cities the vast majority of their income derived from rural properties. In the fourteenth century the Dukes of Lancaster were, invariably, the richest men in the land besides the king. Those men who made their money from trading tended to be drawn from the 'lower' classes. I am sure however that there are exceptions to this.
I do know a fair bit about the merchants who dominated the wool trade, which was by far the most valuable in this period, and they made vast sums of money. This often occurred through illegal or immoral methods, which is my area of study. William de la Pole loaned the king upwards of £100,000 for his wars in France. It was common for these men to transition from these positions of accumulated wealth through trade into land holding nobility. William de la Pole's descendants married into the royal family and become Dukes of Suffolk. They were heavily involved in dynastic politics which are too numerous to outline here! This tendency to transition away from merchant classes is one reason which has been posited to explain the later Dutch dominance over the English merchant classes.
The English Nobility in the Late Middle Ages: The Fourteenth-century by Chris Given-Wilson
William de La Pole: Merchant and King's Banker: Merchant and King's Banker (1366) E. B. Fryde