On Monday, Taco Bell's former CEO officially took over as Chipotle's top executive.

While both Taco Bell and Chipotle serve burritos, the chains are extremely different.

The new CEO could bring changes such as new menu items, breakfast burritos, more advertising, and boozy drinks to Chipotle.

Chipotle's new CEO is coming from a very different type of Mexican-food chain: the fast-food icon Taco Bell.

On Monday, ex-Taco Bell CEO Brian Niccol officially stepped into his new role as the struggling chain's top executive. Taco Bell experienced a period of impressive growth under Niccol's leadership, as the CEO pushed for creative marketing and wild new menu items, such as the Naked Chicken Chalupa.

While both Taco Bell and Chipotle serve tacos and burritos, the two chains' reputations and strategies are extremely different. Chipotle needs a change, however, as it has struggled to win back customers following an E. coli crisis more than two years ago.

Niccol will bring a very different perspective from his time at Taco Bell — and that's expected to affect how Chipotle runs its business. Here are the changes customers can expect with Niccol in control of Chipotle.