Application
Software
Application software or Applications are what most people think of when they
think of software. Typical examples include office suites and video games. Application
software is often purchased separately from computer hardware. Sometimes applications
are bundled with the computer, but that does not change the fact that they run
as independent applications. Applications are almost always independent programs
from the operating system, though they are often tailored for specific platforms.
Most users think of compilers, databases, and other "system software"
as applications.
User-written
Software
User software tailors systems to meet the users specific needs. User software
include spreadsheet templates, word processor macros, scientific simulations,
and scripts for graphics and animations. Even email filters are a kind of user
software. Users create this software themselves and often overlook how important
it is. Depending on how competently the user-written software has been integrated
into purchased application packages, many users may not be aware of the distinction
between the purchased packages, and what has been added by fellow co-workers.
Source : Wikipedia