As mentioned in the comments, there is a difference between the version of the Maven Ant tasks used in Eclipse versus the one used on the command line. Eclipse seems to be using a newer version of this library in which the method DependenciesTask.setPathType(String) exists whereas the command line is relying on an older version.
You may be able to get more information on which version of the Ant tasks Eclipse is using by checking the preferences page. Try navigating to Window -> Preferences -> Ant -> Runtime and see Classpath tab for external libraries.
On the other hand, from the output of the Ant build:
[echo] Executing maven build on Developer machine (other machine)
parsing buildfile jar:file:/C:/Apps/ANT/apache-ant-1.9.5/lib/maven-artifact-ant-2.0.4-dep.jar!/org/apache/maven/artifact/ant/antlib.xml with URI = jar:file:/C:/Apps/ANT/apache-ant-1.9.5/lib/maven-artifact-ant-2.0.4-dep.jar!/org/apache/maven/artifact/ant/antlib.xml from a zip file
the command line is obviously using version 2.0.4 which is located in the lib folder of the Ant home directory. Checking this page, the latest version is 2.1.3 which does contain the missing method. So it would make sense to update the version in the Ant lib directory to be the latest one (check the download link on the project page).
This definitely helps point me in the right direction of a fix, but something is still missing. Something that the command line is doing that eclipse isn't is trying to call both the artifact file and the ant-tasks file assigned to the project in consecutive order: parsing buildfile jar:file:/C:/.../apache-ant-1.9.5/lib/maven-artifact-ant-2.0.4-dep.jar!/org/... with URI = jar:file:/C:.. parsing buildfile jar:file:/C:.../ant/lib/maven-ant-tasks-2.1.3.jar!/org/... with URI = jar:file:/C:...
oddly, I can actually see all the classes needed loading when that maven-arifact jar is not called.
@JustinGrant I think maven-ant-tasks-2.1.3.jar and maven-artifact-ant-2.0.4-dep.jar are the same library. They're just two different versions. Are you saying that the command line is parsing these two Jars at the same time? If yes it means both are referenced on the classpath -- you should only use one, preferrably the newest.
That is what I'm saying yes. It's parsing both, and the second one last. I think we're on the same page.