What are the differences in the functions and mechanisms of action between helicase and topoisomerase in DNA replication and repair processes?

Helicase unwinds the double-stranded DNA during replication by breaking hydrogen bonds between base pairs, while topoisomerase helps relieve the tension and supercoiling that occurs ahead of the replication fork by cutting and rejoining the DNA strands. Both enzymes play crucial roles in DNA replication and repair processes, but they have distinct functions and mechanisms of action.