What is the difference between “+-” and “\-” in maven dependency tree output?

Those symbols do not have any meaning whatsoever, they are just present to read the output of the tree better!

Here’s a more complex output to see better what it does, on a spring-webmvc dependency:

[INFO] +- org.springframework:spring-webmvc:jar:4.2.2.RELEASE:compile
[INFO] |  +- org.springframework:spring-beans:jar:4.2.2.RELEASE:compile
[INFO] |  +- org.springframework:spring-context:jar:4.2.2.RELEASE:compile
[INFO] |  |  \- org.springframework:spring-aop:jar:4.2.2.RELEASE:compile
[INFO] |  |     \- aopalliance:aopalliance:jar:1.0:compile
[INFO] |  +- org.springframework:spring-core:jar:4.2.2.RELEASE:compile
[INFO] |  |  \- commons-logging:commons-logging:jar:1.2:compile
[INFO] |  +- org.springframework:spring-expression:jar:4.2.2.RELEASE:compile

Consider the dependency tree as levels: the first level correspond to the direct dependencies; the second level corresponds to the transitive dependencies of those direct dependencies, etc.

Basically, if there is more than one dependency on the same level for the same artifact, a +- will be shown, otherwise a \- will be shown, indicating an “end” of the tree (i.e. a path leading to a leaf).