In Canon he had a few months with obiwan and a couple weeks with Yoda. Beyond that any of his training was self taught
In later legends books he did meet a couple Jedi that survive order 66 but that was post endor.
Fact is Like had very very little training. Vader like Kylo and Rey toyed with him on cloud city and could have easily beat him.
On the death star not so much. Luke beat a Sith Lord with 15 years or Jedi training and 19 of Sith training under his belt. Keep in mind Sith Lords are the cream of the crop of force users in the Galaxy. Vader himself killed hundreds of Jedi with years of training. Between 5 and 6 Luke was reading Obi wans journal, going on missions for the rebellion and planning Hans rescue.
You can believe it's different but it really isn't. Normally I don't like to unleash my encyclopedic knowledge of star wars but the "facts" and criticisms of star wars fans make me chuckle.