One team are the defending champions, the other are ranked 13th in the world.
One team are among the most successful to ever play in the World Cup, the other have never gone beyond the quarterfinals.
Despite the imbalance in statistics and odds between the Black Ferns and Spain, neither side are approaching their World Cup opener here in York as anything given.
With less than 24 hours before kickoff, both teams were well versed in that practised humility so common in sport, that most superstitious of pursuits.
"We take it week by week," Black Ferns prop Amy Rule said. "We can't underestimate oppositions, because it is a World Cup and everyone is here to win,
"It's more than a game for them and for us, and we've got to do it justice by throwing everything into it."
Last time the two teams met was in 1998, with New Zealand running away 46-3 winners.
The Black Ferns have won six out of eight World Cups. Spain missed out on the 2022 tournament altogether.
The statistics that differentiate the two teams are stark, but few admit to paying any heed to them. Black Ferns attack coach Tony Christie was similarly reluctant to tempt fate.
"We can't take anyone lightly in this tournament," he said. "The rank doesn't mean a lot.
"For teams that come up against the black jersey, they always play their best game and they'll play to their greatest potential, so that's what we're expecting," Christie said.
The Black Ferns begin their defence with a radically overhauled team from their last test in July, in what many see as something of an experiment or a warm-up ahead of more difficult matches in September.
They also enter their defence as an away team unburdened by the expectation that rests with hosts England, who have been ranked No.1 for a phenomenal 249 weeks.
The 'Red Roses' opened the tournament on Friday night with a ripsnorter of a match before a soldout crowd in Sunderland, where they demolished the United States.
On Saturday, they were poring over where they fell short - a sloppy start and missed scoring opportunities.
To have 62 on the board wasn't enough, they said, with hooker Amy Cokayne promising the team would become even "more clinical".
Watching that game intently in their Victorian-era hotel down the A19 in York were the Black Ferns, awash with a veritable smorgasbord of emotions - nerves, excitement, trepidation, the weight of expectation, the surrealness of being about to take the field at a historic event.
"It's the pinnacle, this is what we've been building towards," Rule said. "I love World Cups.
"Everyone is coming together to throw everything they've got at it. It's a great opportunity."
Christie said: "We saw England play their typical style. For us, it gave us real energy for our game tomorrow and what will come in the tournament."
For several years now, the Black Ferns have honed a brand of attack rugby, heavy on pace, endurance and domineering physicality, but Christie was well aware other teams - England, in particular - had shifted their game too.
"I think last World Cup, [former coach Wayne Smith] used an all-out attack method, which was the right strategy and won the World Cup," he said. "Since then, the defences around the world have really grown, and the importance of that kicking game and getting the balance right.
"We still want to be unpredictable, but at times, we need to be able to kick long, and build pressure through our kickchase and defence.
They need to get through 80 minutes in York first.
On Saturday, the team had a final practice run at a local rugby club, going through drills in a park shrouded by trees slowly giving in to autumn's hue.
After that run, news broke that halfback Maia Joseph had injured her hamstring and would miss the match.
"She'll be sweet for the tournament," Christie said. "It's more precautionary than anything major."
Iritana Hohaia was named as her replacement.
Around the corner and across the medieval wall were the Spanish team, holed up in their hotel overlooking the River Ouse, where ducks and swans swam beneath drooping willow branches.
'Las Leonas' are in York brimming with belief, determined to demonstrate a team on the ascendancy.
The current WX3 and European women's champions have gone through a resurgence.
A growing grassroots competition has had some sports journalists asking: Is Spain rugby's next great superpower?
Probably not at this tournament, but head coach Juan González said they had sights set on the long term and they were ready to put up a fight.
Besides, stranger things have happened in sport.
"I think we've got the energy to play the Black Ferns," he said. "I think the unity of the team is very good.
"We would like to show that unity in terms of defence and impact. [The team are] good ball carriers, they make a lot of metres.
"It's a great opportunity to show that we can hit, that we can tackle, to show the team has unity and commitment."
Only four of the Spanish team have ever played in a World Cup before and a baptism of fire awaits at the York Community Stadium, but it's also a team stacked with rising talent, including Claudia Peña, 20, who has courted attention for her performance with English club Harlequins, named Player's Player of the Season in her debut year.
"We will battle every game," Peña said. "I think we will fight every ruck and every tackle.
"I think, when we get into the flow, when we play how we know, I think we can surprise with that."
Appearing in the first World Cup in eight years, Las Leonas feel they have something to prove and no better place to do that than against the reigning champions.
"Obviously, [we'll] play with passion and try to force them to make mistakes, and build some confidence during the game," González said. "I think that will be really good."
The final hours before an opening match at a pinnacle tournament bring an odd array of rituals - some meditate, some listen to music, some have an early night, others lie awake restless.
"I like to tan," Rule said.
At both team camps, there was a sort of nervous calm of athletes pursuing that undefined headspace known as 'the zone', but at Black Ferns HQ, they all shared one particular ritual.
"We have a jersey presentation, which is always very special," midfielder Amy du Plessis said. "It's a huge part of the Black Ferns, and I know each and every one of us... never take it for granted.
"There's a few girls in this World Cup that it is their first time, so tonight will be a very special occasion."
