One is manager of a club which has spent the square route of nothing in this transfer window, while the other has already splashed out £131million, £59m of that on one player, Angel de Maria.
Deila came from relative obscurity in Norway, where his claim to fame is taking Stromsgodset from the second division to the championship.
Van Gaal's CV stands scrutiny against the very best managers, with clubs like Ajax, Barcelona and Bayern Munich, titles in Holland, Spain and Germany, Champions League success and even two spells in charge of the Dutch national team.
But after a night when they saw their new clubs suffer embarrassing cup exits, they stand united in one thing.
Both Deila and Van Gaal have recognised the squads they inherited this summer at Celtic and Manchester United respectively were simply not good enough to meet the demands placed on the clubs.
They both insist they need time to make the big changes required. But while Van Gaal's well-established reputation will afford him patience and time from United's fans, Deila is very much on probation in the eyes of Celtic supporters.
His credentials are being scrutinised more than ever by people openly questioning if this job is too big for him.
The defeat to Maribor had one bookmaker rushing out to proclaim Deila was now 2-1 favourite to be the first SPFL manager to lose his job.
There is no danger of such a knee-jerk reaction from his employers. The Norwegian can ignore such publicity-seeking opportunism.
But the headlines Deila can't dismiss are the ones highlighting his failure to steer his team through to the Champions League group stages not once, but twice.
In hindsight, perhaps it might have been better if, after being comprehensively beaten by Legia Warsaw in the previous round, Uefa had left well alone and allowed Celtic to head down into the Europa League play-offs.
But the Hoops got a second chance, and blew it in quite spectacular style against a Slovenian side which will struggle to make any impact in the Champions League.
That said, without any significant strengthening of the Hoops side in the final few days of this transfer window - a forlorn hope now - would Deila's side have been good enough to win any of their games in the group stages?
REMEMBER, Celtic won only once, against Ajax at home, and lost their other five group games last season when they had a manager with European experience and a squad significantly better than the one at Deila's disposal.
Even so, the income and prestige from being part of today's Champions League draw in Monaco would have outweighed anything else for the club's fans and those who count the cash.
Yet, from the manager's perspective, dropping to the Europa League could provide a bit of the breathing space he patently needs. The calibre of opposition will be lower, and, while Celtic would have been a bottom-pot team in today's draw, they'll be a Pot 2 side in the Europa one tomorrow.
In theory, that should mean an easier group. However, if they perform as poorly as they did against Legia and Maribor, they will still struggle.
When Deila accepted the challenge of turning around a club already heading in a downward direction through a failure to replace the talent it was selling, he was aware he immediately faced a six-game mini-season which would define the entire campaign.
The six Champions League qualifiers and play-off ties were a baptism of fire.
As he rakes over the ashes today, there is no escaping the fact that, on the park, he won only two of those - against KR Reykjavik - drew one in Maribor and lost the other three.
After Tuesday's debacle, Deila was his usual honest self. He admitted Celtic are at present not good enough for the Champions League, and he needs time to get to where he wants to take the club.
Now it is actions, not words, that are required. What the club does between now and the transfer window closing on Monday will be scrutinised closely by those fans whose money they now need more than ever after that bumper Champions League cheque was snatched from their grasp. The legacy of the loss to Maribor is that Deila will have even less cash to rebuild a squad which has more weaknesses than strengths.
By the time Celtic step out on the path to Champions League qualification again next July - after a certain title win - they may be doing so from an even weaker position than this time round.
By then they will have been the victim of players wanting to leave and others refusing to come to Parkhead because there is no top European football to sustain them through the turgid domestic season.
Deila's tough challenge is to ride the storm and produce a side which, without the benefit of serious investment, can compete successfully against Europe's big teams.