shai ban wrote:I am confused between between UBUNTU bootable USB drive and UBUNTU installation on USB Drive.
1) Ubuntu (not UBUNTU) bootable USB (not USB drive) : It is a USB (flash, external hard-disk etc.) which contains the contents of Ubuntu live CD and is bootable. You can plug this to any computer and if you boot from USB, ideally you'll get exact same result as you'll get while running from a live CD. Only thing is - improvement in speed (since access time of USB disk is far less than CD).
2) Ubuntu installation on USB : When you install Ubuntu, generally you do it on a hard disk, right? Same way, if you install it on USB disk (say external hard disk), then it is Ubuntu installation on USB. Here, when you'll boot from USB (where you've installed Ubuntu), ideally, you'll not see any difference between booting from hard disk or booting from USB.
Another difference is space requirements. Ubuntu bootable USB requires almost same size as that of live CD (i.e. less than 700MB). However, Ubuntu installation on USB requires almost same size as it'll take when you install Ubuntu on hard-disk. This size will depend on which packages you install, how frequently you update the system and so on. Generally, it is somewhere around 5-10 GB.
If you are trying this option(installing on USB), then you can allocate larger space on your internal hard-disk for home partition and install the system on USB, or even better, have a big (say 100GB etc.) USB and install everything on it. That way, you can move around with your own OS.
shai ban wrote:Which one will hold my setting made on application like ubuntu browser (firefox)?
Well, the answer is : both. This is because, even if bootable USB behaves like live CD, a major difference is - CD is ROM whereas USB is writable. So, yes, you can save your firefox settings on both.
Btw, it is always a good idea to install OS on your own device (internal/external HD) instead of going on using live CD or bootable USB. Personally, I would suggest to use live CD only if you are a complete newbie to Linux and not sure whether
you should install it on your Windows machine (even then, you can use virtual machine and get a better experience), or if you frequently have to work with dumb terminals (the machines without hard-disk).
I hope this helps.