There are no wiki descriptions for either. I recently posted a question that is sort of a feature but also sort of a change. Should feature-request only be used for new feature requests and change-request be used if the feature already exists and the question is just about updating/refactoring/improving the feature?
[Feature-request] generally refers to the functionality of Area 51. This discussion forum is the "meta" of Area 51, so this is somewhat consistent with how our other meta forums work (i.e. a feature request for the parent site).
[Change-request] is unique to the Area 51 site-creation process. It is used when a user is asking for a change to a proposal that will likely need administrative intervention (e.g. renaming, merges, etc).