digitalocean_spaces_bucket is used to create a new Space (bucket in S3 terminology) and manage Space-wide settings like CORS policies. digitalocean_spaces_bucket_object is for adding an individual file to the Space.

They can be used together. For example:

resource "digitalocean_spaces_bucket" "static" {
  name   = "static"
  region = "nyc3"
}

resource "digitalocean_spaces_bucket_object" "image" {
  region = digitalocean_spaces_bucket.static.region
  bucket = digitalocean_spaces_bucket.static.name
  key    = "remote/path/to/image.png"
  source = "local/path/to/image.png
}

digitalocean_spaces_bucket_object can also be used with a Space created outside of Terraform by specifying its name and region rather than referencing a digitalocean_spaces_bucket