Is Blofeld in previous James Bond movies same as in Spectre

TLDR:

• Spectre is a reboot of the series, so there isn't really a linkage to the Blofeld of old.
• Blofeld is called Oberhauser (which is a completely new name for him, across all the Bond films) for two reasons:
  • To hide the fact Christoph Waltz was really playing Blofeld, to add excitement to that "reveal".
  • As a reference to the novel Octopussy & The Living Daylights where Bond mentioned one of the characters, Hannes Oberhauser, as being like father to him.

Long answer:

Films:

Franz Oberhauser was used to hide the fact that Christoph Waltz was playing Blofeld.

This was because in all the marketing building up to the movie, the film-makers desired this to be a secret. For example, Waltz discussed this in an interview with GQ Magazine:

On whether he is playing the classic Bond villain Blofeld:

"That is absolutely untrue. That rumour started on the Internet, and the Internet is a pest. The name of my character is Franz Oberhauser."

Similarly, Sam Mendes discussed this with Empire¹:

"The B-word! We talk about it all the time. It's the great figure from the Bond vault, as it were," Mendes said.

"There was this big spectre hanging over the movie and the franchise, which is Blofeld, and what happened to the supervillain. That's all I'm going to say."

He added: "There's some big stuff the movie is moving towards. There are depth charges you hopefully don't see coming."

...

"The audience cannot and should not be given - and I'm not confirming or denying anything - information that the characters do not have. And preserving tension in the narrative of a story that is a riff or an acknowledgement of the iconography of Bond over the years has been crucial.

"Otherwise you have taken an audience out of the narrative before it's even begun."

So the reason he was named Oberhauser was to hide the fact he was really Blofeld. This is why the name Oberhauser didn't appear in the previous films.

Books

In the final Bond book (the collection of short stories Octopussy & The Living Daylights, Bond goes to Jamaica to apprehend a WW2 hero who has been implicated in a murder involving Nazi gold.

Most of the book is told through the viewpoint of Major Dexter Smythe, in a series of flashbacks.

We learn Smythe murdered a Gestapo officer near the end of the war to steal the gold and enjoy a life of rich decadence in Jamaica. The Gestapo officer guided him up the mountains to where the gold was buried, and is then shot in the head by Smythe. The officer's body falls off the mountain and on to a glacier far below.

The Nazi officer was called Hannes Oberhauser.

Twenty years later, his corpse is discovered. The investigators worked backwards and realised Smythe had committed the murder.

Bond then explains why he was interested in being the one to apprehend Smythe:

"But how did you get mixed up in the whole thing?"

"MOB Force was a responsibility of my, er, Service. The papers found their way to us. I happened to see the file. I had some spare time on my hands. I asked to be given the job of chasing up the man who did it."

"Why?"

James Bond looked Major Smythe squarely in the eyes. "It just happened that Oberhauser was a friend of mine. He taught me to ski before the war, when I was in my teens. He was a wonderful man. He was something of a father to me at a time when I happened to need one."

Conclusion

Mendes has clearly used this small reference from the novels and expanded on it in the films to create the linkage to Franz Oberhauser and Blofeld.

^{1 This link is to Digital Spy, who reference the Empire article - not Empire themselves, as you must complete a survey to access their article.}