I want to dual boot ubuntu on preinstalled windows 10 but when i watch few videos on youtube I saw some are dual booting alongside windows and some are doing by manually partition(something else). what is different between alongside installation and by doing something else
When you choose dual boot along-side of the windows linux is installed on the largest unallocated space
whereas, choosing manually partition you can manage the partition size and then install on the partation of your choice.
See furhter desription here
When you install Ubuntu, you are asked to chose
install along side, which is basically automatic way of installing ; you let the installer allocate swap ( the hard drive space used for extra working memory ) and how much hard drive space to use for Ubuntu.
something else option you are in control of how you want to organize hard drive space. For example, I don't need swap for solid state drive, so I used
something else option to create only main ( aka root ) partition where my OS resides, and no swap. Some users use it to create separate partitions for
/home directory, which is same as
Users folder on windows .
In short , if you don't plan doing anything fancy with your hard drive, you probably don't need
something else option.