Lancaster is slim and soft-spoken; Johnson is barrel-chested and loud. Lancaster picks his words precisely; Johnson has all the precision of a John Prescott wielding a blunderbuss. Lancaster could be cast as a village schoolmaster; you suspect Johnson would be happier as the village idiot.
And yet, as the Six Nations looms, the parallels are quite striking. A year ago, Lancaster, newly-installed as England's caretaker coach, led his side into the Calcutta Cup match with expectations at their lowest in years. They had been humiliated a few months earlier, held up to ridicule as they lurched from one crisis to another. Lancaster had a brief to rebuild the side, but to some his appointment looked like a desperate measure.
Which is pretty much the position Johnson is in right now. Whatever the official line from Murrayfield, there is no escaping the fact that he is a hastily-appointed caretaker who has been put in charge of a rudderless rabble of a team.
Scotland may not have descended to the levels of drunkenness, debauchery and dwarf-throwing that were England's pastimes of choice at the 2011 World Cup, shortly before Lancaster's takeover, but their performance against Tonga at Pittodrie in November would leave little room for doubt that the wheels had come off somewhere on the road up to Aberdeen.
Can Johnson fix them back on? The word from within the squad is that the Australian has won over the players, but it is one thing to be popular and quite another to be successful. And, frankly, Johnson's record as head coach of inter-national sides is not exactly impressive, neither Wales nor the USA having made noticeable strides during his periods at the helm.
In fairness, he starts with the decided advantage that it would be almost impossible to make Scotland any worse than they were on that calamitous afternoon against Tonga. Or, for that matter, to plumb depths lower than those they reached against Italy in the final match of last season's RBS 6 Nations Championship. But he still has a mountain to climb.
Lancaster conquered his like one of the great Alpinists, assembling his team carefully and mapping out his intermediate goals. But he was helped by the almighty dollop of good luck he had in that first match against Scotland at Murrayfield, when the Scots butchered more chances than had ever been laid before them in a Calcutta Cup match. Lancaster's sheepish grin afterwards was almost an admission that his side had got away with larceny, but it was a result that still set them up for a hugely impressive run in the tournament.
Johnson dismisses comparisons with the scenario Lancaster faced last year. He is right in the sense that the pathways they both took are very different, but the similarities are still striking. And nothing links them more powerfully than the fact that, for all they might talk of building for the future, they had no option but to play the hands they were dealt – and, to a significant extent – the players they inherited as well.
Of course, Lancaster had three new caps in his starting line-up (and another four on the bench) that day, but he was actually less radical than he might have been, the completion of the World Cup cycle a few months earlier having produced the usual crop of retirements. However, Lancaster was acutely aware of the need to pick his players up after a harrowing period, and for all that Johnson's manner is very different, he clearly appreciates that point as well.
"I could be the best technical coach in the world, but it is a people business we are in and understanding people is the heart of that," Johnson said. "It is about understanding who people are and accepting who they are.
"That human element has to be catered for; it is a large part of the job of head coach. I think that more and more the older I get. We are all looking for a 1% edge, and there is a human part in everything we do. That side needs to be catered for.
"I have learned down the years that your loyalty and your bond is with the team you coach. You are working with them day in and day out. You see them at their best and their worst, their frailties and their strengths. You see it all. Living that experience, your loyalty is with them. You want them to experience what they deserve."
For a man better known for his bombast, these were peculiarly subtle remarks. Incisive, too. Johnson may have brought 10 uncapped players into his Six Nations training squad, but he is not going to beat England by pitching them all in at once. Instead, he will have to rely on the majority of players used by his predecessor Andy Robinson. The tried and lately untrusted.
In any case, he can play the good cop so long as Dean Ryan is around as assistant coach. On a couple of occasions last year, there was a distinct suspicion that Robinson had lost the faith of much of the dressing room, and the first thing Johnson must do is win that back. Being the players' mate will not take him all the way to Six Nations glory, but it might get some positivity back in the camp.
And then? The big job starts now, as Johnson finalises his side to face England. Decisions, decisions. Will he dare to hand a start to Sean Maitland, the new recruit from New Zealand whose Glasgow performances have not exactly matched his billing? Will he risk going without the leadership skills of Al Kellock if he reckons Jim Hamilton is the better option in the second row?
And can his charm work its magic on players like Ross Ford and Greig Laidlaw, whose form has taken a dip this season?
Robinson was fond of saying that Scotland could only beat rugby's major nations if every player was at his very best. Nothing has changed on that front.