Hitler didn't initially have the same sort of macabre glee about the war in the West that he did about the war in the East against peoples that he saw as subhuman and a political threat. In the West he wanted defeat, compliance and alliance. In the East he wanted extermination and enslavement. It's a minor distinction. Once war gets started of course all bets are off. But before the attack on Russia an order did go out to the Wehrmacht that the new war would be fought by different rules.

Yeah, Hitler really did see Germany and Great Britain as cousins. He was influenced by British "thinkers" such as Houston Chamberlain and others.

Fun Fact: Hitler and JRR Tolkien were both at the Battle of the Somme. Imagine if Tolkien had been able to shoot him then and save everyone all that trouble

Tolkien did say he carried a grudge against Hitler ("that ruddy little ignoramus") for perverting all that was good about the Northern Spirit.