Why do some Omega OEM straps have CVZ product code but other have RUZ?

For example, I found a Alligator Rubber Strap ( RUZ005421 ) with clasp 025STZ005266 on Japan Mercari so I don't think they are fake. https://jp.mercari.com/shops/product/8vZBjkYEhiD3XeehjKVjP4

This is the first one I found with RUZ. Anyone knows what's the dif?

Does OEM deployant clasp also has something beside STZ?