Some ammo is more accurate than others. In pistols, most people won't ever know which is which because properly evaluating the ammunition requires a very accurate pistol and either a very accurate shooter or someone willing and able to test the ammo carefully from a rest.
In my experience, most any ammo that is good enough quality that I would allow its use in my guns produces satisfactory accuracy.
Here's a 10 round group I shot at 15 yards with an STI GP6 using 6 different kinds of budget practice ammo all fired into the same group.
The entire group, all 6 different kinds of ammunition, measured only 2 inches in size.