Both mean the same thing. So why the different endings, and which is correct?

"Theatre" is the British spelling. Like "shoppe" and "colour." Noah Webster, of dictionary fame, preferred spelling words the way they sounded. He also advocated an "American" language and changed "theatre" to "theater."

So "theater" is the American spelling. Or is it? A majority of San Diego theaters are Theatres (the Old Globe, the Rep, Diversionary, Lamb's, etc.). This is also true around the country and almost across the board on Broadway.

Diversionary Theatre in University Heights

A theory, which may be just snooty speculation, holds that "theatre" is the more dignified spelling. If a theater is just a "theater," it doesn't take itself seriously (or won't sound sufficiently British, where they take theater seriously). The -re implies art. The -er, something less.

The Old Globe Theatre in Balboa Park

That's the high buck approach. It also could be a case of popular usage trumping correctness. "Theatre" has a much longer tradition. That's how Shakespeare spelled it, in fact.

But here's the tricky part. "Theatre" reigns as the spelling for companies. But use it in everyday writing and it sounds like 'thea-tah," and you'll sound like ten kinds of snob.