As it says in the site JacksonFAQ:
Jackson is "100% JSON" and does not try to imitate or emulate XML. Property name mapping is based on standard Java Bean naming convention (although can be overridden using annotations or custom naming strategy).
There are some support compatibility features -- such as ability to optionally use JAXB annotations -- but fundamentally Jackson is a pure JSON/Java data mapper and tries to minimize impedance between JSON and Java data models.
And it continues JacksonFaq#JAXB:
Jackson supports some level of interoperability with JAXB API (javax.xml.bin):
With Jackson 1.1, it is possible to use JAXB annotations in addition to (or instead of) core Jackson annotations
JAXB API, stands for Java Architecture for XML Binding, using JAXB annotation to convert Java object to / from XML file
JAXB is bundled in JDK 1.6 and above so it's not necessary to add any other jars.
Here is a test that says that Jackson is faster but I have not checked the code and its results Test
