I'm really confused as LDD has been last updated in 2015 where as Studio still gets new updates with new parts being added (putting aside from that Studio runs a lot smoother and is actually usable with my latest Mac software even if I wanted to use LDD). Though I do know that LDD has some parts Studio didn't use such as the bigfig parts like the dinosaurs or some minifigure head accessories. Even though Studio is the jack of all trades for me, it still has gallons of missing bricks, especially bionicle parts. Thanks for the link btw, I'll have to check that out!
I actually have an entire download page where the parts have been converted to .part files which includes parts not in Studio that can be imported through PartDesigner: https://bricksafe.com/pages/Cyborg_Samurai/parts-not-in-studio-custom-parts#