What is the difference between templates and Apps?

Good question!
Before there was an Appstore with Apps, most "templates" used an integration from our platform BotProphet.
But now, with the integrated flowbuilder actions in the Appstore, we use subscriptions for the Apps (much like Apps in Shopify store). The template is given for free with the Apps subscription.
There's not a BIG difference in the functionality of the old template vs the New method, but the Apps are newer and MUCH easier to use for you since it is 100% integrated in ManyChat's flowbuilder.
You'll find an overview of all existing Apps on this page: https://manyapps.io