In general networking control plane is used to exchange the destination information whereas data plane is used to program the control plane information in the local stack along with the information how to reach to local neighbors. But in the world of SDN networking, SDN is always referred as separation of control and data plane. At high level, SDN controller can be OPENFLOW or PCE based controller.
But most of Network Planning Engineers always stumble to understand which controller is best for the network.
OpenFlow, where centralizing the control plane of the network usually requires full upgrades and/or replacements of significant parts of the network, PCE rather introduces an evolutionary approach towards a centralized control of the network infrastructure. In the beginning, only the edge layer of the network needs to support PCEP, while the network may continue using traditional ways of signaling (such as RSVP-TE) and same schemes for mapping traffic to paths at the edges, as shown in the figure below. There is no need for controller to communicate to all network elements in the path, as it is the case with OpenFlow
So in nutshell, if you are planning to deploy OPENFLOW based controller you have to upgrade the entire network and has to manage the state of OPENFLOW in each and every router where as in PCE based controller only edge routers need to support the PCE rest network upgradation is not required.
PCE vs OPENFLOW