Hi Francois,
i dont think anybody will answer your question because you missed few words in it. Is your concern if there is difference between i-doit and iTop? There are differences between these products since they come from different companies. Have a look on features for each product to see details.
http://www.combodo.com/-Features-.html
http://www.i-doit.org/en/about-i-doit/83-2/
J.