An AWS CloudWatch event bus is a feature that facilitates AWS accounts to share events with each other.Amazon CloudWatch event buses are configured to allow access only to friendly AWS accounts in order to prevent unauthorized users from sharing their CloudWatch events. This is AWS best Paractice to notifiy if the Amazon CloudWatch default event bus created within your account allows unknown cross-account event delivery.
An AWS CloudWatch default event bus is a feature that facilitates AWS accounts to share events with each other. This is template notify if your CloudWatch default event bus available within your AWS account allows access to everyone (*). This is AWS best practice to allow only the authorized users to send their events data by managing the permissions defined for the default event bus.