Ubuntu is completely free to download, use and share. Ubuntu 14.04 LTS has been released on 17 April 2014. Ubuntu is distributed on two types of images, desktop image, and server image. The desktop image allows you to try Ubuntu on a graphical user interface that most end users want to use. But in the server image, the graphical user interface will not install.
Release Notes :
https://wiki.ubuntu.com/TrustyTahr/ReleaseNotes
Full Download Link :
http://releases.ubuntu.com/14.04/
There are four images available which two for server and two for desktop.
1. Server install image for 64-bit PC (AMD64)
https://releases.ubuntu.com/14.04/ubuntu-14.04-server-amd64.iso
2. Server install image for PC (Intel x86)
https://releases.ubuntu.com/14.04/ubuntu-14.04-server-i386.iso
3. Desktop image for 64-bit PC (AMD64)
https://releases.ubuntu.com/14.04/ubuntu-14.04-desktop-amd64.iso
4. Desktop image for PC (Intel x86)
https://releases.ubuntu.com/14.04/ubuntu-14.04-desktop-i386.iso