OfBiz 4.x and opentap

[abhishek jain]

Hi friends,
Is there any book for ofbiz 9.x , i have found a book for ofbiz 4.x though.
Is there any major difference between the two.
Also what is the difference between ofbiz and opentaps.
Also i need to setup a customized ecommerce sol with multiple store, will
you advise me to modify the ecommerce module of ofbiz or setup / develop a
new one, and where can i find the feature list of Ofbiz and an official
manual or so.
Pl advice ,
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Thanks and kind Regards,
Abhishek jain