There's no difference between Ellas and Capellas as far as I can tell (
vaping some right now). I'm not sure why they renamed it. I like HD for trying new flavors, since they sell the small bottles for $1.99. It's not the best deal per ml, but it's a good way to try lots of flavors without a big investment.
ETA: I think the code for HD is 2YEAR. It's for 20% off. I just made an order there a few days ago.. stocked up on some WL nic, and picked a few new flavors to try. I think I'm going to just get my WL nic from HD from now on. HD has better flavors (IMO), and I'm tired of dealing with WL always being out of stock.