A producer is very hands-on at all stages of production. The producer is involved in casting, script development, hiring the crew, managing the film's budget, dealing with day-to-day issues that arise during shooting etc. While the director oversees all creative aspects of the production, a producer supervises the business/logistical side of things.
An executive producer on the other hand is often an investor who has made a financial contribution to the film but does not become involved in the day-to-day running of the production. The title executive producer may also be more honorary than real. Sometimes it is bestowed on the film's stars as part of their contract. A production company or studio executive that had some initial involvement in the project might also be given the title of executive producer as a kind of thanks.
An executive producer on the other hand is often an investor who has made a financial contribution to the film but does not become involved in the day-to-day running of the production. The title executive producer may also be more honorary than real. Sometimes it is bestowed on the film's stars as part of their contract. A production company or studio executive that had some initial involvement in the project might also be given the title of executive producer as a kind of thanks.