Google Data Transfer
Data Transfer Service
Service that helps you to transfer data from either a Google Cloud Storage bucket, an Amazon Simple Storage Service (S3 bucket), an HTTP/HTTPS location, or on premise infrastructure to a Google Cloud Storage bucket.
It is recommended for transferring more than 20TB of data or data that would take more than a week to upload.
You can use gsutil for transferring data from on-premises location, while using console for transferring data from a cloud storage provider.
It can be scheduled and configured through a transfer job.
Request Transfer Appliance
It sets up Transfer Appliance, i.e., a high capacity storage server within GCP, allowing you to securely transfer your data there.
It is recommended for transferring more than 20TB of data or data that would take more than a week to upload