If you're deploying a brand new community to an org that doesn't have communities enabled, then you must first set
NetworksEnabled as a part of the
OrgPreference Settings metadata.
When you create a community for the first time Salesforce will generate some Apex classes, EmailTemplates, and Visualforce pages automatically. These are used to facilitate self-registration, logging in, and notifying community members.
To deploy Communities, there are a few necessary pieces of metadata:
Network - The core Community/Experience settings
CustomSite - Settings for a Site like whether it's Active or has a URL Prefix.
SiteDotCom - this is a binary BLOB that contains most of a Community's content (pages, assigned layouts, components on the page and their set values). Note that you can't really compare this because it's binary and in order to deploy this to a target the source must be on the same API version as the target otherwise your deployment is dead on arrival because the only solution is to wait for the target to upgrade. Also note that simply fetching this metadata from the Salesforce Metadata API can generate a brand new MD5 hash so it's difficult to tell if there are differences between two communities.
If you have ExperienceBundle enabled for your community (under Setup > Digital Experiences > Settings), then the
ExperienceBundle metadata consolidates the three key pieces from above into one, easier to read & deploy metadata type.
Then there is metadata for branding (look and feel):
NetworkBranding - core community branding, such as the login page colors and background
BrandingSet - for branding themes (colors, fonts, brand image)
ContentAsset - asset file metadata, like a logo image
Finally there are a few optional pieces of metadata related to Communities:
Using any tools that access the Metadata API (ANT & Gearset come to mind, but pick your preferred tool) should allow you to compare all of these pieces of metadata together to spot differences with the exception of
SiteDotCom. With differences in the source and target, you'll probably need to either construct a unique deployment file (to merge changes from both into one) or align all the changes in QA and then deploy to production.