What is the difference between those options?

1. www.limesurvey.org/manual/Iterate_Survey

2. www.limesurvey.org/manual/Limesurvey3#New_features

The second link refers to a previously planned version of LimeSurvey, which has been deprecated. The current develop branche at Github has the "new" version 3.0.

github.com/LimeSurvey/LimeSurvey/tree/develop (live and most up to date, changes every day now...)

Please test it, as it is a development that is near a release canidate, the developers need people to test it and report back experiences and errors.

Do not use it for production purposes, it may have unrecoverable errors.

Tammo