How can I compare a live website/software with its design to identify bugs?

I recently redesigned a software for my company, and it has successfully gone live in production. However, I want to ensure its quality by comparing it against the original designs to identify any discrepancies, such as issues with padding, color, text, or spacing.

What methods or software tools do you recommend for effectively comparing live software with its design? Are there any best practices or alternative approaches I should consider? Any insights or experiences would be greatly appreciated!