title: Why do sender and minter should be same on minting NFT?
body: <p>I am developing NFT marketplace with terra and I use CW721.
  And I noticed on mint function if the sender and minter is not equal it returns &quot;Unauthorized&quot; error.
  I can ignore this condition but is this required?</p>
  <pre><code>pub fn mint(
          &amp;self,
          deps: DepsMut,
          _env: Env,
          info: MessageInfo,
          msg: MintMsg&lt;T&gt;,
      ) -&gt; Result&lt;Response&lt;C&gt;, ContractError&gt; {
          let minter = self.minter.load(deps.storage)?;
  
          if info.sender != minter {
              return Err(ContractError::Unauthorized {});
          }
          ...
      }
  </code></pre>
  <p>In Javascript with Terra.js I sent request with my wallet address.
  But if the sender and minter must be same, I have to send request with minter's wallet address.
  And that means NFT creator should know the password of minter's wallet.</p>
  <p>What's the difference between token_uri and image url?
  I think they are same.</p>