Princess VS NCL: If you don’t drink wine then the regular beverage package is similar to NCL’s. You should be able to order most mixed drinks. Nothing beats the NCL Premium Plus package IMO (bottles of wine at meals). The specialty dining is very similar to NCL - Crown Grill is like Cagneys and Sabatini’s is like La Cucina. There are not as many venues, both dining and bars, on Emerald Princess. You may find on the older Princess ships evenings are more subdued than NCL with fewer options for entertainment. The food in the main dining room is comparable IMO.
There seem to be more pools and hot tubs on Princess ships with a nice aft adult-only pool on your ship. I compare the older Princess ships with the older NCL ships like the Sky. There are no slides, climbing walls or the like on Princess ships.
I enjoy Princess especially if I want a relaxing cruise at a good price. Enjoy your cruise!