Both Maven and Ant are build tools, and predominantly for Java projects. Here is a quick summary of what are the salient differences between the two:

1. Encapsulation vs Procedural: Maven associates a single build artifact (e.g .jar file) with a maven project (in a folder). Moreover to keep things simple, it provides guidelines on how source and test folders should be structured. Ant leaves it up to the programmers to define the structure and flow of build.xml as they see fit.

2. Version maintenance of artifacts. This is probably most important feature of maven which directly affects day to day work of developers. All jar files and artifacts are versioned and it makes it difficult for developer to make a mistake in picking a wrong version.

3. Repository maintenance. Though nothing stops developers and CM folks to maintain a repository of artifacts built using ant, it is not an in-built or supported feature of Ant. But maven relies on repository of artifacts as a core feature of project oriented management of build artifacts.

4. Dependency maintenance. With explicit versioning and repositories, it becomes easier in maven to manage dependencies. Indeed this is where all things start coming together and one beings to see the rationale of why things are done in certain 'fixed' ways in Maven.

In short, Ant allows a free procedural kind of scripting mechanism for build, and over time, ant scripts can become unwieldy and tougher to maintain than acutal business code! Which is where maven tries to simplify things by providing encapsulation, clear structure, dependencies, and a design for configuration management, than a mere build tool.