Every Morgan and Peace dollar has a VAM which is a description of the die pair used (obverse and reverse) when that specific coin was minted.
Some VAMs are more desireable and / or rare and may carry a price premium over the same year and mint mark but made with different dies.
What is interesting about the VAM side of collecting is that not all of the die combinations have been catalogued as a few new ones are found each year, researched and assigned a new VAM.
VAMing opens a whole new aspect of collecting. When you start to examine the fine details of the coin, it connects you back to the person who engraved the die as you can see the work of their hand. You can see how a planchette was prepared and handled prior to minting. You can see the mechanical flaws of the machine used to stamp the coin and you can see the progression of the die state and how it changed and deteriorated in the process.
For me, I basically was acquiring coins to build sets. Now, I am searching for and collecting coins that have specific features and flaws, many of which are frequently overlooked by most collectors.