UCaaS and CCaaS both move communications into the cloud, but they solve different operating problems.
UCaaS connects the workforce
Unified Communications as a Service typically combines business voice, meetings, messaging and collaboration for employees.
CCaaS manages customer interactions
Contact Center as a Service focuses on routing, agent workflows, quality management, analytics and customer channels such as voice, chat, email and SMS.
Integration creates context
When the platforms share presence, directories and business data, organizations can move customer issues between agents and subject-matter experts more smoothly.