Differences Between AN
and AP Propellant

ANCP with R45HT or R20LM binder is easily produced without need for vacuum unlike some faster APCP formulations (containing CuO, Mg etc.).

Advantages:
AN is much less sensitive to impacts than AP and generally safer to use.  
AN is environmentally safe.
AN is commonly available.
AN is cheaper than AP.
Long-burn sustainers are easier to produce.

Disadvantages:
AN is hygroscopic and must be kept dry.  Baking the AN at 150 deg and mixing it while warm is useful to keep moisture at a minimum and density high.
ANCP must be kept dry during production and storage.  (However, very long term storage is possible in heat sealed plastic bags.)
Phase stabilized AN should be used if long term storage is contemplated with temperature cycling through about 90 deg F.
ANCP has a lower density than APCP and usually requires one case size larger for the same weight of propellant.
ANCP is more viscous during production.
AN requires Mg instead of Al and Mg is more expensive than Al.
ANCP is a little more difficult to light than APCP.
Slower pressurization may be a factor for heavy rockets and accelerometer based altimeters requiring kick (rapid onset of acceleration - high rate of change of acceleration).

ANCP propellant has lower burn rates than APCP.  Therefore, to produce comparable thrust, several measures must be taken.

With advances in binder/curatives and the above steps, optimized ANCP propellant with a specific impulse similar to or even exceeding that of typical commercial APCP hobby motors can easily be produced. However, if you need higher specific impulses or higher thrust for heavy rockets or boosters in multi-stage rockets, then optimized APCP would be more suitable.