Yes, there is a difference. You can sell the posters and memorabilia, or display them publicly as you please. There is a restriction as the material cannot advertise another product or service, as Disney probably still has the trademark on the characters displayed, or it could be inferred that Disney is endorsing your product.
Films and music are different. Just because you own the physical media doesn't mean that you can present them. This applies whether or not you charge admission. However, as you only have a PD trailer, you should be fine exhibiting it. If you exhibit it as part of a larger program, you could probably even claim "fair use" of the trailer.
