You are planning an infrastructure refresh for a payment processing platform that still runs several critical services on a legacy UNIX environment, while newer services already run on Linux. Before committing to a migration plan, you need to explain the practical differences between UNIX and Linux in a way that informs execution decisions around compatibility, support, cost, and operational risk.
What are the key differences between UNIX and Linux, and how would those differences affect your execution plan for migrating or operating production systems?