Explanation
https://cloud.google.com/architecture/private-cloud-networking-for-vmware-engine Dedicated Interconnect provides a private [1][2], dedicated connection between your on-premises network and Google's network. It offers low latency, high bandwidth, and a secure connection. Partner Interconnect provides a connection to Google Cloud Platform through a partner's network, such as a service provider or a carrier. It offers the same low latency, high bandwidth, and secure connection, but is slightly slower than Dedicated Interconnect.
References: [1] https://cloud.google.com/interconnect/docs/concepts/types [2]
https://docs.vmware.com/en/VMware-Cloud-on-AWS/services/com.vmware.vmc-aws.networking.doc/GUID-6D