Difference between google_iap_web_iam_member and google_iap_web_iam_member

Hello,

Can anyone explain the difference to me between this set of resources https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/iap_web_iam and this set of resources https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/google_project_iam ?

Why would I use the web_iam set of resources? I have found some documentation that suggests that web_iam does not need to be set at a project level but I’m not quite sure what that means and there don’t seem to be any examples demonstrating why thats useful.

For context I have some gke and compute applications behind IAP and I’m wondering which of these terraform resources I should use to give access.