A writer and producer of Star Wars Rebels has confirmed that Captain Rex (of Clone Wars and Rebels) is the bearded rebel that leads the troops in the final ground assault on Endor.
http://screenrant.com/star-wars-rebels-captain-rex-art-return-jedi/
Given that the Shuttle Tyderium included a bearded rebel, does that mean we can now retrospectively speculate that they are in fact one in the same?