Go to your local store and buy several items of the same product – say a package of three golf balls. Though the golf balls appear identical, closer examination will reveal ever so slight differences. One ball maybe fractionally larger; another ever so slightly less spherical; perhaps the third is ever so slightly lighter. The generality that extends from this is that any two seemingly identical products will have nevertheless slight variations in their properties.
Now buy a packet of three electrons (or their antimatter equivalent, the positron). Each electron, or positron, will be identical in size, mass and electric charge to as many decimal places as you care to measure. All electrons (and positrons) are 100% absolutely identical clones.
Take one electron and one positron and bring them together. They annihilate releasing a fixed amount of energy. Take another electron and another positron and repeat the scenario. The pair will annihilate releasing an identical amount of energy in the process. The amount of energy released in each electron-positron annihilation case is the same, to as many decimal places as you can measure. That’s quite unlike taking a match from a box of matches, striking same and releasing its stored chemical energy as heat energy. Another match from the same box wouldn’t release, to as many decimal places as you care to measure, the absolutely identical amount of heat energy.
How come identical golf balls aren’t but identical electrons (or positrons) are?
Electrons (or positrons), having mass, can be created from energy (just like mass can be converted to energy as in the case of the electron-positron annihilation process). You (human intelligence) can’t create identical golf balls, but a seemingly non-intelligent natural process (Mother Nature by any other name) can create or produce copies of a fundamental particle, like an electron (or positron), that are clones of one another down to the nittiest-grittiest detail.