What is the difference between Import/Export vs Dataflow

Question

So, I'm using Magento 1.6.2.0 on a project and I'm seeing I have options for import, export, and dataflow profiles. In previous versions I've used the interface has been like the dataflow profiles. What is the difference between these, and what are some scenarios which I should be using each one?

The reason I'm asking is because I've been trying to import products with new images and it's not working whatsoever. Using the Import feature it's all going through without any error messages. When I try to import the same file using dataflow, it gives me errors about the images not existing, and there are also other errors since it looks like the exported data using the export feature isn't in the proper format to import using the dataflow profiles. I can't find any information in the forums or anywhere else, so maybe someone can shed some light for me.