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How do isobars differ from isotopes?

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What are isotopes and how do they work? — isotope An overview of isotopes.

The primary difference between isotopes and isobars lies in their atomic composition and chemical identity:

Isotopes are atoms of the same chemical element that share the same atomic number (number of protons) but possess a different number of neutrons. Because they have the same atomic number, they occupy the same position in the periodic table and exhibit nearly identical chemical behavior, though their physical properties and atomic masses differ.1
Isobars are different nuclear species that share the same mass number—the total sum of protons and neutrons in the nucleus. Unlike isotopes, isobars represent different elements because they have different numbers of protons.21

In summary, while isotopes are variations of the same element with different neutron counts, isobars are distinct elements that happen to have the same total mass number.21