GCP offers various pricing schemes that vary per service. Broadly there are 7 types of pricing

Free Trial
A risk free trial period, with specific limitations
On sign-up to GCP we get 90 days free and $300 Free Credit
At end of trail have to upgrade to a paid Billing account to continue using GCP
Has some limitations on services : Can’t add GPU to VM, Can’t use Windows Images, etc.

Free Tier
Services that have minimum monthly limits for free use
Services like : App, Engine, Compute Engine, Cloud Storage, BigQuery support this tier

On Demand
Pay for resources using a consumption based model (Pay for what we use)
Ideal for short-term, spiky, unpredictable workloads

Committed Use Discounts (CUDs)
A lower price than on-demand for agreeing to a 1 year or 3 year contract
This pricing tier is available for Compute Resources (vCPU, Memory, GPU, SSDs)
Ideal for workloads that have predictable workload needs

Sustained Use Discount (SUD)
Automatic discounts for running specific Compute resources for a significant portion of the billing month
This pricing tier is applicable to specific Compute Resources (vCPU, Memory, GPU)
Pay only for the number of minutes that the instance is used
GKE and Compute Engine uses this pricing automatically
Not available for App Engine Flexible Environment and Dataflow

Flat-Rate Pricing
Prefer a stable cost for queries rather than paying on-demand pricing (Only BigQuery)
To enable this feature we need to use BigQuery Reservations

Preemptible VM Instances
Instances with deep savings but at the cost of being interrupted
They can be alive for no longer than 24 hours
They can be preempted by GCP with a 30 sec notice

Sole-Tenant Node Pricing
Sole-Tenant Node (Single tenant virtual machine) is a physical Compute Engine server that is dedicated to hosting only our projects VM instance
SUD discounts are applicable by CUD discount is not applicable for this service