Amazon Nova is a foundation model created by Amazon and is offered as one of the models you can use in AWS Bedrock, so the model gets a marketing page for it. Note that Llama also has an AWS marketing page (as do other models), but that doesn’t make them AWS products: https://aws.amazon.com/bedrock/llama/

Amazon Nova Chat is a different product that uses Nova, buts it not AWS. Notice that if you try to use Nova Chat, you log in using your Amazon.com account and not an AWS account.