What's the real difference between Dynamics 365 Customer Service and Dynamics 365 Contact Center?

I’m trying to wrap my head around how Dynamics 365 Customer Service and Dynamics 365 Contact Center actually differ in practice. There’s a lot of overlap in features like AI, omnichannel support, and integrations.

For those who’ve worked with either (or both), what are the real-world differences in terms of features, workflows, and use cases? And how do you decide which one fits best for which customer?