Why are there different numbers on golf balls?

I mean what is the difference between a Titlest 1 and a Titlest 5?Why are there different numbers on golf balls?
It is the soft-nest of the ball. So someone with a rather soft swing would want a 1-3 and a hard hitter would want a 3-6. Also the temperature has a lot to do with this. On hot days i prefer a harder ball but on cool days i take a soft ball. (it has nothing ot do with telling them apart, it is just convenient)Why are there different numbers on golf balls?
I think it has to do with softness of the rubber used to make the ball
The numbers are solely for identifying your ball. Some don't have numbers any more, for instance, the Strata, it has card figuers on it, like hearts, diamonds, spades, and clubs.
So you can tell your ball from someone else playing the same brand ball.
I'm sure there is a scientific reasoning, but also so players can distinguish between their ball and their partner's ball!
So that golfers with golf balls from the same company can play together without confusing one ball for the other.