The difference is in how lithium batteries need to be charged. Been a while since I read up on them. But the requirements are totally different than what we used to need to do.
I have a cordless drill that's about 5 years old, maybe older, with a built-in Lithium Ion battery. 14.4 volt homeowner grade Black & Decker. Until I bought that, I was only using contractor grade 18 volt drills with the removable NiCad batteries.
The charger for my last one quit working & I was about to buy an 18 volt DeWalt when I saw that one. The "lithium batteries" written on the box made me immediately pick it up. I looked at it for all of about 10 seconds before deciding on it, just because of it's battery. Best drill I've ever bought. At 14.4 volts, it's not as powerful but it makes up for it in usability because of the battery. My first cordless drill was a 12 volt Ryobi. It's comparable to that one in torque, maybe a little better.
The battery isn't removable though. When it's dead, you can't just pop in another battery, so that part sucks.
But I've left it in the barn for months & months then grab it & it's running full strength through a whole project. When it "dies" it simply stops. One second it's going full strength then it just stops like it's completely dead. Charge it for 10 minutes & you can use it again at full strength to finish a job. It doesn't get that shallow cycle memory like the NiCads.
The only advantage to the NiCad drills is you can swap batteries in 2 seconds & keep working. But if you take your "dead" battery & put it straight in the charger, it'll shorten the charge/discharge cycle. You have to use the flashlight to drain it completely before charging it.
The only thing I don't really know about my lithium battery drill is how it compares to a comparable size NiCad in terms of amp hour ratings.
