There are quite few differences actually

* DTube is a crypto streaming video platform on the Steem Blockchain where users can upload their videos and earn in the payouts of Cryptocurrency (Steem & SBD)

* Whereas Youtube has the same feature of uploading and sharing contents but has censorship issues and many more restrictions than Dtube and the once you get to earn from youtube you will be paid in USD most of the times.

* While Dtube is add free and does not has  other hassle like youtube. 

* Dtube helps Content creators who makes quality Video with the form of Upvotes thus the users get a handsome payout compared to the new users of Youtube.

* Here in Dtube both the viewers and content creators can earn rewards by upvoting the content of the users in the form of curation reward(you have to have id in Steem Blockchain). Which for the viewers in Youtube not possible.

* No one can shut you down in Dtube with any issue one of the great advantage compared to youtube. You will have no issue in uploading contents. 

This are the most basic differences.