Container runtime Vs orchestrator
A container runtime is the part of your container environment in charge of the creation and basic features of your containers. The obvious one is Docker, but you can also find Containerd, CRI-O and other as runtime for your containers. 

An orchestrator, by contrast, will not exactly create your container (ie, an orchestrator is not the technology used to create them). An orchestrator will use your container runtime to manage them. In a way, it's a layer around your container runtime wich allow finer usages, such as scaling, multi host deployments, load balancing...

The most famous orchestrators would be Kurbenetes, Docker Swarm...

I hope this help! Have fun.