AirBnB handholds the traveller from the moment they start looking to when they're going on the trip. CL just presents an ad, and lets the parties email/text on their own. AirBnB handles the financial transactions, with all that that entails, and CL does not. AirBnB facilitates the communication between the landlord and the customer. They also let you add on "experiences" as part of your trip. They also include an identity verification system for both landlords and consumers, and there's a review/rating system for both. It might not be perfect, but Craigslist has nothing like it. For example, I generally avoid renting places that don't have reviews, and landlords can choose to ignore/reject renters who have built up a bad reputation.
CL, on the other hand, has a reputation for being full of scammers and other shady people.