We have a lot of Dewalt stuff at work. I think the chuck in the new 20V is crap compared to older 18V drill. Don't know that either battery is better. Just got some new packs for the 18s and I think they last pretty good. I had similar experience with Ryobidrill from 3-4 years ago dropping bits at previous job.
I think some are 'made to order' under different part #s. Usually very minor changes from other tools. Just so it's harder to make direct comparison of features and cost.