Pod-network-cidr and ip range allocation in CNI plugin

HI guys, question please, should the --pod-network-cidr be the same as the CIDR range used by weave net? for example if I add the kubeadm init --pod-network-cidr= then the below range in weave should be equal to if not necessary to be the same IP, then the pod will get IP from which subnet, from the pod-network-cidr or weave?

I cant understand why we need the pod-network-cidr if the pods are getting IPs from the CNI plugin