Multi language: Multiple tree and single tree?

Question

In TYPO3 (https://typo3.org/), there are two approaches for multilingual websites known as the "One-Tree" and "Multiple-Trees" approach.

The Multiple-Trees approach is no problem in Craft CMS: I know sites, sections and field translations.
But I have no idea for the One-Tree approach? (Don't know if it's even possible ...)

Multiple-Tree

The Multiple-Tree approach means that the different languages have no connection to each other and switching to another language loads the respective homepage.
Pros: Very flexible, because of separate pagetrees for each language.
Cons: No control of the translation status, especially for larger websites.

One-Tree

The One-Tree approach means that when switching the website to a different language branch, the corresponding content for the other language is loaded automatically. If there is no translation available, the corresponding content of the default language is displayed. One page hosts all languages.
Pros: Good overview of the translation status of all pages in the backend.
Cons: All languages share the same pagetree (kind of inflexible).

Example from TYPO3

Answer 1

Edit: After the screenshot above was added in an edit, I realise that this question might have more to with how multi-site entries are managed in the control panel, and less with how the content itself is modelled, or how it's exposed on the front end.

The short answer is that, no – there is no side-by-side or equivalent view for multi-site content in Craft, that is equivalent to the One-Tree TYPO3 view pictured above.

In Craft, propagated multi-site entries can be switched between via the site dropdown in the top left corner of element edit pages and indexes.

Original answer (doesn't really answer this particular question, but the info might still be useful to someone coming to Craft from TYPO3):

I'm not familiar with TYPO3, but based on your description I'd say the closest equivalent to the One-Tree/Multiple-Tree concepts in Craft lingo is the term "propagation method" – i.e. in multi-site Craft installs, content can be configured to propagate across different sites, in different ways (or not at all).

Sections (and Matrix fields) can be configured to propagate (or not) using mutiple different propagation methods. For example, you might have a section where all entries are propagated to all sites, another section that only propagates its entries to sites in the same site group, and even a section that doesn't propagate at all (i.e. equivalent to "Multiple-Tree"), etc.

It's even possible to configure a section to let content authors optionally propagate specific entries to different sites, i.e. letting the content author decide if a particular entry should be available in multiple sites or not.

Essentially, this means that in Craft, you can combine the One-Tree and Multiple-Tree approaches to multi-lingual content, and use one or the other (or combinations of the two), when and where it makes sense to any particular piece of content.

Regardless of your approach to multi-lingual content modelling, the strategy for switching languages in the front end is completely up to you. To that end, it's completely possible to build a language switcher component that conditionally redirects the user to the same entry in the chosen language, or to the selected site/language's base/homepage URL if the current entry doesn't exist in that site/language.

Here's an example for such a language/site switcher component.

Additionally, plugins like GeoMate can be helpful in building language switchers (check out the craft.geomate.getSiteLinks() method).

I'd also recommend reading the "Sites & Localization" guide in the official Craft docs, for a good overview on how multi-lingual content is approached in Craft.