Comparisons between both moves by Hitler and his Nazi govermnment of the Saarland and Sudentenland are full of revisionist reviews.
The Sudentenland was taken over after the invasion by Poland and Germany of the newly emerged state known as Czecheslovokia. There were german speakers who favored the freedom offered by the Czech goverment. There was no vote. It was a province of the the old Austrian Hungary kingdom and histocially German princes supported the Czech king.
The Saar was a different story. When Hitler held his plebicite 80% of the Germans there voted for being reconected with the united Germany formed under Bismarck it was removed along with Alsace (Strasbourg which is across the river) as reparations to France after WWI. After WWII another vote was again held under the strictest of supervision and again 80% voted for its return.
Sorry about the double post.