What’s in a name? A lot of confusion.

Two Boston film festivals are headed to federal court over claims that one of them — the Boston International Film Festival — has trampled on the trademark of the other — the Independent Film Festival of Boston — by changing its dates and the name of its website in a way that misleads the public and causes confusion about which film festival is which.

The suit was filed this week in US District Court by the Independent Film Society of Boston, which runs the Independent Film Festival of Boston. It alleges that the Boston International Film Festival’s actions have caused “a false and misleading impression’’ that the two festivals are somehow connected.

Attempts to reach Patrick Jerome, executive director of the Boston International Film Festival, were unsuccessful Friday.

At issue is Jerome’s decision in 2009 to move the date of the festival, from summer to spring, within a week or so of the dates of Independent Film Festival of Boston, and then, last year, changed the festival’s website, from BIFilmFestival.com to BostonIFF.org, which resembles the Independent Film Festival’s URL IFFBoston.org.

“I want to be clear, we don’t have any issue with the Boston International Film Festival,’’ IFFBoston executive director Brian Tamm told us. “The issue is the way they represent themselves online, on Facebook, with hashtags, and on e-mail. We feel pretty strongly there’s confusion between our two brands.’’

As a result, according to the lawsuit, the public and some filmmakers have difficulty distinguishing between the two festivals, tweeting at one when they mean the other or submitting material to the wrong festival.

Tamm said he’d hoped to resolve the matter without going to court.

“We contacted them and their response was, sort of, ‘We’ve decided to change it and that’s the way that it is,’’’ he said. “We made a friendly phone call and sent a friendly e-mail, and then we sent a slightly more serious e-mail and a cease-and-desist letter that they didn’t respond to. So the lawyers filed a complaint.’’