You don't have an owner's manual that came with the car..? Or check the gas cover, sometimes it's written inside the recommended type of fuel. Push comes to shove best to ask an authorized dealer for your make of car.
The car will run on both Octanes at the pumps and it will not cause any damage to the engine; it might just not run so efficiently but you probably would not notice it unless on a race track.
Higher octane would reduce the chance of knock, but you'd know it pretty soon if 95 wasn't enough for you.
Higher octane may be "preferred" on those cars that have sportier engines, use forced induction and the like. i.e. the more refined models that run combustion to more delicate tolerances.
A 323 should do fine with 95. 95's fine for the other Mazda's from around that age group that use 1.6l engines and the like.
It will run on everything just it might be less efficient for engine but you won't notice it. Why won't you ask at the petrol station, they will tell you exactly which one.
95 Octane (unleaded) fuel is the standard fuel grade in most of Europe. 98 RON (super unleaded) is also widely available and is more expensive. As a guide, unless your engine is particularly high performance, it's not worth going for 98- you wouldn't notice any (tiny) power increase, smoother running or better fuel economy. The owner's manual would state the need to run on 98 RON fuel if it makes a reasonable difference.
Just make sure it isn't diesel... made the mistake of putting petrol in a diesel car when I first moved to Germany (since we generally have no diesel vehicles in the great white North) Expensive mistake... oops!