Hey @seancruikshankidelta, A product expert might have additional info for you about specific differences, but it looks like the Splunk Insights for AWS Cloud Monitoring is aimed at AWS customers who don't have a Splunk environment already and offers dashboards and solutions 'in a box' that make it really easy to monitor migrations to AWS using Splunk.
They are fundamentally the same software. It depends on the delivery mechanism. Splunk Insights for AWS Cloud Monitoring is the Amazon Machine Image available from the AWS Marketplace. The Splunk App for AWS is the default app in Splunk Light, either on-premises or in Splunk Light Cloud.