No, "Om" and the Christian cross are not equivalent symbols.
Om (also spelled Aum) is a sacred sound and a spiritual icon
in Hinduism. It signifies the essence of the ultimate reality,
consciousness, or Atman (soul). It is considered to be a symbol of the universe
and the underlying cosmic sound that sustains it. Om is used widely in Hindu religion and to a certain extend in Buddhism, Jainism, and Sikhism, but its significance may vary slightly across
these traditions.
On the other hand, the Christian cross is a symbol
representing the crucifixion of Jesus Christ and is central to Christianity. It
represents the sacrifice of Jesus for the salvation of humanity and is a symbol
of faith, redemption, and divine love for Christians. The cross is not directly
comparable to Om in terms of symbolism or meaning.