Ah, spring is in the air, and that means baseball season is upon us once again. Spring training is underway, and Opening Day won’t be far behind, ushering in months of action on the diamond from the 30 teams in Major League Baseball. It also means the debut of Sunday Night Baseball on NBC and Peacock, where you’ll be able to catch many of the biggest games of the year. 

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Watch Sunday Night Baseball on NBC and Peacock.

And as with every major professional sport, a new season means the arrival of new fans, whether we’re talking about people just getting into the game, or those casual fans who are set to get more invested as their favorite players shine. The point is, some viewers will have questions, and we’re here to help, so let’s take a look at a basic one: Do Major League Baseball’s American and National Leagues have any major rule differences?

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What are the American and National Leagues?

OK, let’s back up for a minute. Yes, Major League Baseball is one organization, but within it there are two leagues, the American League and the National League. As with other pro sports, these leagues grew out of the sport’s earlier days, when baseball leagues sprouted up all over the United States with the hope of building a following. 

By the end of the 19th century, the American League and the National League (which is the older of the two) were the clear giants in the baseball world, so the leagues agreed to share the spotlight, joining together for the World Series at the end of every season and sharing the revenue and media attention that came with what would eventually become the modern MLB.

But despite this agreement, for much of their history, the AL and the NL operated as largely autonomous units. With the exception of the World Series, interleague play wasn’t a major part of the game, and each league had its own quirks and rules which leant their own character. For example, the American League was known for its scoring, while the National League was more of a pitcher’s playground, with a focus on strategy and defense. 

At the end of the 20th century, though, after decades of operation as separate entities, the American and National Leagues legally merged into the Major League Baseball organization that we know today. 

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What are the rule differences between the AL and NL?

The merger of the two leagues into the MLB more than a quarter century ago had a number of impacts. Interleague play became more of a standard practice during the regular season, players were more likely to move between leagues via trades and free agency deals, and most importantly, rules were standardized across the two leagues. 

That means that, as of 2026, there are no major rule differences between the two leagues when they take the field. The last major rule difference was the universal Designated Hitter rule, which allows teams to sub in one designated hitter for their pitcher during each game. The American League adopted the practice in the 1970s, while the National League was resistant to the change. In 2022, universal Designated Hitter rules were standardized across both leagues, marking the last major rule change to arrive post-merger. 

So there you have it. The American League and the National League pretty much play by the same rules, which makes it that much easier for a new baseball fan to keep track.