What is the difference between a User Experience Designer, Information Architect and Visual Designer?

1. No. If a visual designer is not doing research (generative &/or validative), contributing to the structure and behavior, and overall strategy of the connection points between the human beings and the system, then they are not a UX Designer. UX != "feeling". That being said a solid UX Designer SHOULD be a visual designer as well, but doesn't have to be. 
   
   
2. Research, structure, behavior. Artifacts may vary, thinking shouldn't.
   
   
3. They can ostensibly be the same thing depending on the organization and the roles and deliverables assigned. 

-- dave

Dan Saffer wrote elsewhere on the web:

User Experience Design is the general term under which all types of design (visual, interaction, sound, industrial, etc.) fall. Even fields like architecture, writing, HCI, information architecture, ergonomics, and a host of others could all be considered UX, because they are all concerned with the overall impression a user has when engaging with a product.

So to call yourself a user experience designer you should cover all these sub-disciplines. There is overlap between the sub-disciplines and it's not uncommon than one person is responsible for visual and interaction design, or for interaction design and information architecture. But I think few designers are so all round that they can cover the whole field in a professional manner and call themselves ux designer. For excellent ux design you will need a ux team with several designers specialized in one or more of the sub-disciplines.

- Yohan

The title UX Designer can mean just about anything. I think more important than can you use a "UX Designer" title to describe a visual design role is, will the title communicate what both job seekers and hiring managers expect? I think most people who are looking for a job title of UX Designer will be disappointed if all that is expected/needed is someone to do visual design. As a hiring manager, if I were looking to fill a purely visual design role, I would be concerned that someone with a UX Designer title on their resume might not be suited for the role.

When I see job titles (either in job posts or on someone's resume), until I read the details of the responsibilities, I read User Experience Designer, Interaction Designer and Information Architect as the same. Most people don't get to pick their own job titles and many people creating job titles don't really know what people do.

To be clear, there is a difference between information architecture and interaction design, but they are often done by the same person in one role with either job title (or another one altogether, like User Experience Designer).