IPINA is especially intended to decision trees induction (says also Classification Trees). Use TANAGRA if you want other kind of analyses such as clustering algorithms, svm, factorial analysis, statistical hypothesis testing, etc.
SIPINA is a Data Mining Software which implements various supervised learning paradigms. SIPINA is an academic tool, it is free for all kind of activities.
SIPINA is distributed on the web since 1995, it runs under Windows OS (W95 and later) . My main preoccupation is to build an experimentation engine for research activities.
SIPINA is mainly a Classification Tree Software (specialized on Classification Trees algorithms such as ID3, CHAID, C4.5, ASSISTANT-86, etc....). But, other supervised methods are also available (e.g. k-NN, Multilayer perceptron, Naive Bayes, etc.). We can perform perfomances comparison and model selection.