Sorry I thought I told you....
ZZ is the code for sheilded, dirt can still get in but the bearingis mostly covered and only open by a very small amount near the inner race. The nice thing about ZZ is you fill the cup inside the end bell with grease before you slid it all back together it will "pump" some gease into itself, but if that gears becomes fowled with dirt or water that could be a down side.
2RS is a fully sealed bearing, use it never grease, it and toss it when it gets noisy...
As far as the LL type in NTNs, I can't be sure what that means. I've nerver used a NTN there's nothing wrong with an NTN but I only use FAGs or SKF I know and completely trust them. I've changed what seems like thousands of motor bearing over the years and can only think of one case that FAG let me down, in the early 90s when somebody made a boo-boo at the factory and some were shipped with the grease in the 2RS lot.
Doug