Thanks for your request! Here’s a nice and dense comparison of both products at slant.co. For a closer look how draw.io handles UML diagrams, please refer to that article:
https://support.draw.io/display/DOB/2016/04/28/UML+State+Diagrams+with+draw.io
Hope this is detailed enough to fit your needs. Feel free to reply, if you need further information! 
