Lightroom :: 4.1 - Difference Between Exporting And Printing To File?

I'm using LR4.1 on OSX 10.6.8. I convert my NEFs to DNGs at import, do my edits in LR. Most of the time when I want to create output it's for screen use. I use "Export" and produce JPGs.
 
But when I'm preparing files for printing at the lab, I use the Print module, and Print to File, because I like to create a JPG where the image size is smaller than the paper size, for framing purposes. For example, I use the Print module to output a JPG where the "cell size" is 11x14 but the "custom file dimensions" are 12x18, then I have the lab use 12x18 paper, leaving me a white border on my print that makes it easier to mat and frame.
 
Two questions, really.
 
1. Does LR do anything differently as it creates a JPG, depending on whether you use Export or "Print to File"? I'm assuming not, but just wondering.
 
2. Is there a way to do what I want to do -- create a JPG where the picture is one size but the paper size is larger -- through the Export dialogue (like ideally, through an export preset) or do I indeed have to go through the Print module to do this?
 
No emergency here, my method is working for me. (Though using an export preset to do what I'm doing, rather than having to go through the Print module, would be a little quicker, I suppose.)