They are the same thing in that they're both desiccated hormones. NP is sometimes considered a generic for Armour. The actual T4 and T3 amounts are supposed to be the same, but the fillers/binders are different because they're made by different manufacturers. You might do better on one or the other.
If you did better and want to go back to the NP, tell your pharmacy to do that or try a different pharmacy.