Atoms of an element differ from those of all other elements in atomic number and electronic configuration.

Atomic Number:
The atomic number of an element is the number of protons in the nucleus of an atom. Each element has a unique atomic number, which determines its position on the periodic table. Atoms of different elements have different numbers of protons, and therefore different atomic numbers. This is the fundamental characteristic that distinguishes one element from another.

Electronic Configuration:
The electronic configuration of an atom refers to how its electrons are distributed among different energy levels and orbitals. The electronic configuration determines the chemical behavior and properties of an element. Each element has a unique electronic configuration, which is based on the number of electrons it has. The arrangement of electrons in the atom's energy levels and orbitals is specific to each element.

Distinguishing Elements:
1. Atomic Number: The atomic number defines the identity of an element. It determines the number of protons in the nucleus, which in turn determines the element's chemical properties and behavior. Elements with different atomic numbers are fundamentally different from each other.

2. Electronic Configuration: The electronic configuration of an element determines the arrangement and distribution of electrons in its atoms. It affects the element's reactivity, chemical bonding, and overall behavior. Different elements have different electron configurations, which make them unique.

Example:
Let's take the example of two elements, carbon and oxygen. Carbon has an atomic number of 6, which means it has 6 protons in its nucleus. Its electronic configuration is 1s2 2s2 2p2, indicating that it has two electrons in the first energy level and four in the second energy level.

On the other hand, oxygen has an atomic number of 8, with 8 protons in its nucleus. Its electronic configuration is 1s2 2s2 2p4, meaning it has two electrons in the first energy level, two in the second energy level, and four in the third energy level.

From this example, we can see that carbon and oxygen have different atomic numbers and electronic configurations, making them distinct elements. These differences in atomic number and electronic configuration are what differentiate atoms of one element from those of all other elements.