These are Azure Resource Manager (ARM) templates that install Couchbase Enterprise. simple is probably the best starting point. generator is a template generator for advanced configurations, including MDS and XDCR.
marketplace is the template used in the Couchbase Azure Marketplace offers and probably best deployed directly from Marketplace. Similarly testdrive supports the Azure Marketplace offer and shouldn't be used standalone.
Documentation that covers deploying from Marketplace as well as some best practices is available here.
Useful links are here.