What are the advatages of the jaeger tracing with istio and without istio?
For example with istio it will reduce the latency for collecting the more traces
If you are already using Istio in the deployment, then enabling tracing in it will provide more complete picture of request processing, such as accounting for the time spent in the network between the proxies.
You also don't need to have full tracing instrumentation in your services as long as they pass through certain headers, then Istio can still provide a pretty accurate picture of the traces (but you cannot capture any business specific data in the traces).
Traces generated by Istio will have standardized span names that you can use to reason about the SLAs across the whole infrastructure, whereas explicit tracing instrumentation inside the services can often use different naming schemes, especially when services are written in different languages and using different frameworks.
For the best of both worlds, I would recommend adding instrumentation inside the services for full fidelity, and also enabling tracing in Istio to capture full picture of request execution (and all network latencies).