how are atoms distinguished from another, as in which subatomic particle is used to make the call? electron?

Answer 1

no. what makes atoms different from one another is the number of protons in their nucleus.
that´s why you need nuclear reactions in order to make one element out of another.
electrons are involved in chemical reactions.

Answer 2

Atoms are distinguished only by the number of protons. This number of protons usually called Z is the atomic number.

In the neutral state , this number Z is also the number of electrons