Is the bell tolling for Chipotle?

Nacho fries! Tuscani Pasta! Chicken Alfredo! Posters and sales pitches for Taco Bell’s latest menu additions cover the windows of a store on a busy Manhattan block.

At a nearby Chipotle, however, the signage was more subdued: “Now Open,” it read simply.

The posters are a stark illustration of the deep divides between the two low-priced Mexican-food chains. Fast food — its stream of new menu items, its marketing, its reliance on franchisees — is in Taco Bell’s DNA, while Chipotle has used a simple menu to build a fleet of company-owned stores.

It’s a gulf that Taco Bell’s CEO, Brian Niccol, will have to bridge when he moves to Chipotle next month. Credited with reversing Taco Bell’s fortunes, he must now apply those successes in an entirely different environment, as Chipotle struggles with a plunging stock price and a string of health issues.

“He’s had a very respectable track record at Taco Bell, but I would say that those experiences don’t translate to Chipotle,” said Nick Setyan, an analyst at Wedbush Securities.

In 2011, the year Niccol joined Taco Bell to work on marketing and product innovation, the chain struggled with its own public image problem and sputtering sales. A lawsuit, later withdrawn, claimed the company’s seasoned beef taco filling was more filling