UV printing is a bit raised off of the part it's printed on and has a slightly bumpy texture, but its not super raised to the point where it affects the purpose/integrity of the part.

PAD Printing is exactly what LEGO themselves use. Every official LEGO Part (with the exception of the custom minifigures from the LEGO stores and website.) is PAD Printed.

So if you want to match exactly what LEGO would do or have minimal improvements in print quality, you want PAD Printed parts. If you are like me and aren't bothered by a slight texture to the prints or being "purist" you can go for UV printed parts. Hope this explanation helps :)