Can i install distributions from within ubuntu? (to a different part of the drive, i mean)

I suggest VirtualBox.

VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL) version 2.

You can use it to make virtual drives for each operating systems or Linux distributions.

I don't think it is possible, and not even convenient, because the installation process of various distributions is not particularly long.

Only thing you can try is to install on a virtual disk with virtualbox, then could be possible to move the installation on a real partition, with the required modifications, to fstab and to grub for example, but the process is not simple, and I cannot recall exactly the details.