Can someone with enough reputation suggest them as synonymous?
They do have different purposes. The wikis for each
should be have been updated to reflect that.
- retag-request is to request that one tag be renamed into another; this may also involve the creation of a synonym
- tag-synonyms is for questions about the tag synonym feature of Stack Exchange
- tag-request is to request creation of a tag that doesn't currently exist
- retagging has no questions, so it should get cleaned up by an automated process
If people are misusing these that's a problem with their descriptions, not that they themselves are synonyms.
I have improved the wiki and excerpt for tag-synonyms and the related synonym-request. tag-request has been changed on most other Stack Exchange sites to tag-creation; I've updated its wiki and excerpt and changed the three questions that had the old tag.