So what exactly is the difference between white and clear waterslide decal paper?

White waterslide paper is printed on a white background, whereas clear waterslide paper prints the decal on a clear background, meaning the background will blend in with the printed ink.

The process is the exact same for both white and clear waterslide paper however the application is different.  

Clear waterslide paper works best for white or light colored items. 
White waterslide paper will show more brilliantly on all darker or non-white surfaces. 

However, with white waterslide paper you must be mindful that the white background will show very noticeably if not trimmed properly to the edge.

So what exactly is the difference between an SVG file and a PNG File?

SVG Files are for cutting. These are files you would use on your silhouette or circuit machine. An SVG file can still be printed but its most commonly used as a cutting file. SVG files will always keep a clean crisp resolution.

PNG files are used for printing on sublimation paper, printable vinyl, waterslide decal or even a durable card stock. This type of file will have a transparent background. PNG give you more room for creativity. Keep in mind that that the larger the file is the more pixelated the image will be.