Both are extremely competitive individuals, and while Retallick has traditionally had a harder edge to his game - there are few better at clearing rucks - Whitelock appears to be learning that with his size and technique he can do a lot of damage to the opposition.
The other thing the pair have in common is an almost super-human workrate, a couple of giants in almost continual motion.
Sir Colin Meads, an All Black lock from another era but still considered one of the best players New Zealand has produced, believes Retallick and Whitelock will be counted among the greats once they eventually hang up their boots.
"Whitelock's the all-round player - he's got everything," Meads said. "He's their go-to man from kickoffs, he's pretty keen to take the ball which is always a great sign.
"Brodie's a big rough guy who gets stuck into everything. They're different but both very good.
"They're both pretty fit young guys and they have a tremendous workrate. They can keep it up for 80 minutes if they have to."
Meads added: "There's a lot of depth there now. That was one of our worries a couple of years ago, that we wouldn't have the locks to carry on, but they've really come right.
"I just think New Zealand's lucky that we've got three great locks. They're all young, they're going to be here for a few years yet."
Retallick and Whitelock are both from outside their franchise catchment areas. Retallick was born in Rangiora, North Canterbury, and travelled north in search of greater rugby opportunities. Whitelock, one of four brothers all playing for the Crusaders, was born in Palmerston North and travelled south for similar reasons.
Whitelock's importance to the All Blacks was brought home when he returned early after a finger injury to play in last month's second test against France in Christchurch when Retallick was crocked by a hamstring strain. It was Retallick's first significant injury of his career - his second is the high ankle sprain he has recently recovered from.
Both have made big strides this season, but it is Whitelock who has perhaps made the most significant ones.
Springbok Andries Bekker was talked about as being the best lock in the world before his Stormers team played the Crusaders in Cape Town this season.
Afterwards it was all about Whitelock following a 19-14 victory in which he played a leading role, his carry and offload sending Matt Todd away for his side's only try.
Bekker, all 2.08m of him, was also completely shut out in the lineouts at Newlands.
Meads, who played 55 tests in an extraordinary All Black career which started in 1957 and ended in 1971, said the skill level of the modern lock was a little different to the player running around in his day.
"They're all taller. And with the lifting in the lineouts and all these sorts of things, it's changed.
"They make me feel small - they're all three or four inches taller than I was (Pinetree was listed as 1.92m in his playing days).
"They're big guys and athletic too, they're not big plodders, they're big athletes.
"Whitelock's skill levels are fantastic. He's obviously a great runner with the ball, good around the field and you trust him to take the kick-offs and everything that's going."
If he had to choose between the pair, Meads said he would have to go for the Crusader.
"Whitelock's the all-round player who would give you more over the whole game ... he's developed so much over the last year or so."
And as for who he felt would win the match, King Country stalwart Meads said he had little choice in the matter.
"We're in a Chiefs area here, so we've got to go for the Chiefs, but the way the Crusaders have been playing over the past few weeks is a bit of a worry."
Chiefs v Crusaders
Waikato Stadium, 7.35pm tomorrow
Chiefs: Gareth Anscombe, Lelia Masaga, Charlie Ngatai, Andrew Horrell, Asaeli Tikoirotuma, Aaron Cruden, Tawera Kerr-Barlow, Matt Vant Leven, Tanerau Latimer, Liam Messam, Brodie Retallick, Craig Clarke (c), Ben Tameifuna, Hika Elliot, Toby Smith
Reserves:Rhys Marshall, Ben Afeaki, Michael Fitzgerald, Sam Cane, Augustine Pulu, Bundee Aki, Robbie Robinson.
Crusaders: Israel Dagg, Tom Marshall, Ryan Crotty, Tom Taylor, Zac Guildford, Dan Carter, Andy Ellis, Kieran Read (c), Matt Todd, George Whitelock, Sam Whitelock, Luke Romano, Owen Franks, Corey Flynn, Wyatt Crockett
Reserves: Ben Funnell, Joe Moody, Luke Whitelock, Richie McCaw, Willi Heinz, Tyler Bleyendaal, Adam Whitelock.
