Translation is the replacement of words.
Localization is the feeling that the site was originally created for that country.
According to Shopify, displaying prices in local currency can increase conversion by up to 13%. Users are one-third more likely to complete a purchase if they see a familiar currency.
Source: https://www.shopify.com/enterprise/blog/multi-currency
This results in clones, disparate URLs, competing versions, and cannibalization. According to Ahrefs, up to 60% of multilingual websites have errors in hreflang or structure, which directly affects ranking.
Source: https://ahrefs.com/blog/hreflang-tags/