Spinnaker: is an open source CD platform
Istio: is an open source service mesh which reduces complexity of deployments
What’s a service mesh? It describes the network of microservices and the interactions between them.
Istio also does things like A/B testing, canary releases, rate limiting, access control and end-to-end authentication. But also provides behavioural insights and operational control over the service mesh.
https://istio.io/docs/concepts/what-is-istio/
However, I’m not reading great things about Istio. E.g.