The N or C is a performance parameter. 75 is the group number which defines the physical size of the battery. In your case the N means a reserve capacity of 95 amps at 90 minutes discharge. The C battery you have installed is rated at 25 amps at 90 minutes reserve. So the battery installed has less reserve power than the one specified for the car. The extra reserve would help to start the car after a sustained discharge that could happen while driving slowly in traffic with lights, wipers, heater and radio all going at once and you park it. As in - drive to dinner in the city in bad weather, eat and then drive home. The exra reserve helps re-start after that.
I don’t think you will have any problems but I don’t know what kind of car this is or how you use it.