Words like Incremental, Iterative are quite often used in an Agile environment. In most cases Incremental and Iterative are used interchangeably. However it is not true that they are one and the same.
Incremental is anything that is built in small chunks, however Iterative is much more planned even though it is also built in chunks. Most of the Agile methods we see are incremental and Iterative.
There is also a debate that the current definition of "Iteration" which specifically talks about building something incrementally but in a time boxed environment is the definition introduced by Agilists, and not the true definition.
Brad Appleton has done a lot of research about the definitions and history around usage of Incremental and iterative words. Check this link out for more details