NAT Gateway vs. NAT Instance

• NAT Gateways are more suitable for higher bandwidth requirements than NAT Instance (scales up to 45Gbps). Whereas, NAT Instances depend on bandwidth of instance types
  
  
• Zone independent architecture - Create NAT Gateways in each AZ. This ensures high availability. Whereas in NAT Instances, we have to manage failover between instances using scripts
  
  
• Can we replace NAT Gateways/NAT Instances with a VPN connection?
  
  No. VPNs are used to connect to route traffic in a private network (skipping Internet). NAT Gateways/NAT Instances are used to route traffic from EC2 instances in the private subnet to Internet.