You have to define these two terms first: If you speak of "Multilingual", you mean websites that appear in a single country - but in different languages. Especially our Swiss friends know what I mean. And "Multi regional" means that a page with one or more languages appears in different countries.
Both have their hurdles in the structure of the site structure - but what if both have to be done at the same time? This question is in a User Webmaster Forum at Google asked. He is looking for an ideal structure to help Google through different country pages in different languages.
Specifically, it is in this case the performances of DJs. The site operator wants a Spaniard to be informed about the performances of Paul Oakenfold in Berlin - in Spanish. All right? The solution he proposes is a distinction by country by subdomain and the languages by directory. So:
• English on the English side: en.domain.com/en/
• English on the France side: fr.domain.com/en/
• France on the English side: en.domain.com/fr/
Now, however, he is worried whether some content (eg an interview with Paul Oakenfold - ie regionally independent content) may be in danger of being classified as duplicate content. After all, the same text is written on different subdomains.
In the webmaster forum, SEO services in Lahore the googler John Mu spoke up and said meaningfully: Actually this should not be a problem, but it would be good to select a "preferred" version of the content and put on this a Canonical tag of the other side.
Well, you could make it simple: The German text is to be found on the German side, so we send a Canonical across the border from the English subdomain.
Unnecessary "declassing" of content?
But the American complex culture of European culture is not quite catchy, seems to me. Because if I would like to publish the interview with the DJ in Germany, Switzerland and Austria - should I really be able to leave the Alps to Germany and give me a chance there? Probably not!
What is missing in this answer in my opinion: John Mu does not go to the Google Webmaster Tools. These offer the possibility to assign the content of a complete subdomain to a country. And exactly that is the problem: If the same content is once assigned to Austria and once Germany, Google can indeed distinguish quite well. If there are other experiences among the readers, I would be interested.
Thus, the most complex multi-regional structure on multi-regional sides would be well managed:
• Country pages with subdomains,
• Language versions with directories,
• In the Google Webmaster Tools, make the settings for the subdomains.
Of course, you can also try to simplify the structure and work without the subdomains. This makes the internal linking somewhat more complex - but it will be possible to publish every content really only once. But that was not the content of the question