Re: Edubuntu size differences.
I think Edubuntu used to be an add-on. Starting with 9.10, they made an Edubuntu 'live' installer so users can add the appropriated educational features during the initial setup. I don't know why 10.04 is smaller, but I would imagine it has to do, in part, because not all of the software is finished for the release. If you're new to Linux you should definitely avoid 10.04 until it releases next month.