I am using the metadata tag and tags interchangeable. What I have noticed, if I screen in dataview, either tag should be used or tags.
Is there a way to change all metadata called ‘tag’ into ‘tags’ so that I have one definition to work with?
search and replace plugins, no real solution found
I’m not sure what you mean by “if I screen in dataview”, but you’ll want to use tags: going forward. tag: still works, but is depreciated and will be rewritten to tags: if you use the Properties view UI.
https://help.obsidian.md/Editing+and+formatting/Properties#Deprecated+properties
For mass editing, you could look at the global-search-and-replace plugin or use Sublime Text, VSCode, etc. (how I usually do it).
Either way, always make a vault backup before any mass changes. 
hi ariehen,
This is very helpful! I mean with “if I screen in dataview” filtering on tags: I use: “> table tag as “Tag”” sometimes I do not see Tags and sometimes I do not see Tag.
Anyway thank you for your reply, I will use tags going forward and I will lookinto the global search and replace plugin!
thx again🙏