1) ant.log :

• log created during the build from Apache ANT 1.6.5 from a DOS shell
• the logging is clear, because you can see the targets of the build chain
  being executed, as well as a bit more detailed information e.g. warnings, ...

2) ant_from_idea_default.log:

• log created during the build from Apache ANT 1.6.5 from IDEA 6.05
• most information being logged is useless and confusing (e.g. every
  call to c:if of ant-contrib is being logged)

3) ant_from_idea_with_quiet_option.log

• same as 2), except that the ANT command-line option '-q' (quiet) was passed
• better than 2), but still confusing because the target names aren't being
  logged as in 1)