They are quite different.
Labella RX - Nickel-Plated Steel over hex core, with their "focused string design" (which they don't explain)
Balanced Nickels - Pure Nickel over round core, using "balanced construction" (same # of wraps on each string)
From their writeup, the RX sound like they are more inline with Dunlop Super Brights or SIT Foundations in that very malleable, low tension type of feel. The NPS cover is going to give them some snap while retaining a focused low end.
Balanced Nickels are firm, but not stiff. They're a dark string, because of the pure nickel cover, but retain a little brightness and sheen.