Currently there is no "creative-mode", "builder-mode" nor "creation-mode" available, as Creativerse is still a work in progress, and even after release the development is still ongoing with updates implemented ca. each month.
However the developers have added to the FAQs since 2014 that they are thinking of adding at least something equivalent to a "creation"-mode. No further details of these plans have been revealed as of yet though.
Other modes, world-creation-options and/or difficulty-settings have also been discussed occasionally. If you have any suggestions about how new gameplay-modes like creative-modes could be designed in detail, then please join the discussions on the forums: http://steamcommunity.com/app/280790/discussions/2/