If you simply do a normal software upgrade you will remain on Ubuntu 14.04. You can be certain that an upgrade to the next major release (e.g. 16.04) will always require your confirmation, so you may try to upgrade packets at no risk.
Update the package database using
sudo apt-get update
Then upgrade packages with the command
sudo apt-get dist-upgrade
... or if you are concerned about package dependencies and don't want any installed packages to be uninstalled under no circumstances, instead use
sudo apt-get upgrade
However, upgrading packets will upgrade your system past 14.04.1 (to 14.04.5 currently). The last digit in this release number is not that special though. It is simply a means to periodically bundle together all upgrades that have occurred since the major release so that the ISO you download with the OS will contain current packages. By doing this the OS requires fewer upgrades once installed in order to get to the current state (i.e. to the latest version of all installed packages). Within a major release upgrades normally only contain security and bug fixes and will not introduce much new functionality and not change major version of tools. (Example: Ubuntu 14.04 came with python 3.4. Although newer versions of python are now available Ubuntu 14.04 will not upgrade python to e.g. 3.6 but only upgrade to 3.4.whatever.)
Unless you have a very specific reason not to do so, you really should upgrade packages to avoid security vulnerabilities.
One such reason could be that you have built (compiled) source code that depend on the very Linux kernel version you are currently using. If you do an upgrade in this case and fail to rebuild the software, it may not work when you switch to an upgraded kernel. If this software that you built was e.g. a graphics driver or another kernel module, your system may fail to load normally.
You should also be aware of that Ubuntu 14.04 is soon End-of-Life, i.e. Canonical will stop providing package upgrades to this release. See https://wiki.ubuntu.com/Releases for more information about currently supported releases.