Helium: Helium is an element having the atomic number 2 and is represented by the symbol He.
Hydrogen: Hydrogen is a chemical element having the atomic number 1 and is represented by the symbol H.
Helium: The atomic number of helium is 2.
Hydrogen: The atomic number of hydrogen is 1.
Helium: The atomic weight of helium is 4.002602 amu.
Hydrogen: The atomic weight of hydrogen is 1.00794 amu.
Helium: Helium exists as a monatomic gaseous substance.
Hydrogen: Hydrogen exists as a diatomic gaseous molecule.
Helium: Helium has only 0 oxidation state.
Hydrogen: Hydrogen has -1, 0 and +1 oxidation states.
Helium: Helium has two major isotopes as 3He and 4He.
Hydrogen: Hydrogen has three major isotopes; Protium, deuterium, and tritium.
Helium: The melting point of helium is -272.2oC.
Hydrogen: The melting point of hydrogen is -259oC.