This is because, in Tails, *Tor Browser* is confined using *[[!debwiki AppArmor]]* to protect your files from some types of attacks against *Tor Browser*.
For example, thanks to this confinement, even if an attacker manages to exploit a security vulnerability in *Tor Browser*, they wouldn't be able to access all the content of your Persistent Storage.
<p>To prevent Tails from running out of memory and crashing, download very big files to the <em>Persistent/Tor Browser</em> folder. All the files that you download outside of the Persistent Storage are stored in memory (RAM), which is more limited.</p>
It is impossible to hide to the websites that you visit that you are using Tor, because the [list of exit nodes of the Tor network is public](https://metrics.torproject.org/exonerator.html).
The anonymity provided by *Tor Browser* works by making all users look the same to make it impossible to know who is who among the millions of users of *Tor Browser*.
Tails tries to make it as difficult as possible for websites to distinguish Tails users from other users of *Tor Browser*. If it was possible for a website to determine whether you are a user of *Tor Browser* inside or outside of Tails, this would provide a little bit more information about you and reduce your anonymity.