To answer the OP's question, a spline drive lug has a smaller OD which makes it easier to install in the tight lug cavity of some wheels.
So yes, 12x1.5 in a tapered seat or acorn bulge. I can't remember which seat those wheels have.
This might help. (large image...)
http://www.checkpoint-safety.com/sit...tor_types2.jpg
There are a variety of brands, Gorilla is fine. I have black spline drive Gorllias on my truck.
The reason they're fine and not awesome is the grooves that the key engages the lug.
As you can see, they are rounded, and not very deep.
But they work....
If you want the best of the best (with honors,) McGard Spline drive are the best out there.
The base spins, so it won't gall your wheels and as you can see, the area where the key engages the lug is much higher tolerance with more surface for engagement.
Its $35 vs ~$120
Also there are aluminum lug nuts available, generally used on "tuner" or custom import cars, there are a metric ass ton of styles, colors and variations. I bought some for my truck in red, because I thought it would look cool... ;)
But one completely stripped out without any effort because one of my studs was mucked up. I had no idea until I pulled it off... and I did them all by hand. Aluminum has its place, but I wouldn't trust them on a 4wd application.