Different views, different floor m2 area, carport on one Vs LUG on another. Different floors - top floor commands a premium.
....and that is without even thinking about level of finishes in one Vs the other. (one renovated, the other not...etc)
After all that, you have the motivation of the vendor for selling. Desperate = cheaper perhaps? Different agents giving different advice to different vendors / LL's - the free market in action.