In Classical Mechanics we consider particles as things whose internal structure for the purpose of studying some phenomenon might be neglected. In that setting we associate particles to points and sometimes we picture then as very tiny balls.
In that understanding of particles, they obviously have a well defined position. Also it is a quite easy idea to grasp intuitivelly, after all we see macroscopic things at particular locations.
On the other hand, when we consider the mathematical model of Quantum Mechanics things change a little. To describe a particle instead of giving a location we give a probability distribution which tells probabilities of detecting the particle somewhere.
In that new setting I've found two ways to look at it:
The particle is still as in Classical Mechanics: something we can consider as a point and visualize as a tiny ball. In that way, for some reason I don't know the theory don't allow us to associate it with a particular location.
The idea of particle must be revised, it is not some tiny ball we treat as a point, but rather something spread over a region. In that setting we have to revise what we mean by visualizing a particle to make the statistical interpretation of the wave function make sense.
So which point of view is correct? Considering Quantum Mechanics what really is a particle? And how to bridge the gap between the idea of particle from Classical Mechanics and Quantum Mechanics?