Gatland says Henry indicated to his players at the outset of the trip of Australia who would be selected for the Test matches.
He says that meant his compatriot "lost half the team on day one".
"The players knew straight away what was the Test side and who was making up the numbers," said the New Zealander.
Gatland, who on Wednesday named his side to face the Provincial Barbarians in the tour opener on Saturday, says each of his 41-man squad is in contention to face the All Blacks.
"Keeping harmony in the squad is paramount," he said. "It's about giving everyone an opportunity.
"It's important these guys feel like they are putting themselves in the shop window and have a chance to prove themselves, and with a little bit of luck are in contention for the Tests.
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Owen Farrell and Johnny Sexton appear to be in competition for the fly-half spot after Gatland reiterated he sees the Englishman as a "world-class 10", rather than a centre.
Irishman Sexton starts on Saturday, with Farrell on the bench.
"The players are pretty aware about the competition in that position," Gatland said. "Johnny gets a start on Saturday, and the other two [Farrell and Dan Biggar] will get a start in the next two games."
Gatland's son Bryn will start for the Provincial Barbarians at fly-half.
"I spoke to Bryn last night and he's enjoying the week," Gatland Sr said. "We'll catch up tomorrow, and he'll expect to have to make a few tackles on the weekend.
"We haven't spoken too much about the game but he's excited about the opportunity."

Radioactive cooling water was also mistakenly discharged into a submarine reactor compartment, the Office for Nuclear Regulation (ONR) reported.
Reporting of safety incidents at the base, which refits Britain's nuclear submarines, was "below standard".
Contractor Babcock International said safety was its "highest priority".
The ONR issued a legal notice to improve after an incident last year in which a worker was contaminated with radiation.
The ONR said the dose was "very small" but it "highlighted shortfalls" in health and safety at the yard.
Babcock has been ordered "to bring the arrangements up to an acceptable standard" before the end of January 2016.
The ONR said five other incidents broke safety rules between October and December last year.
They were:
The ONR also reported "shortfalls in the operation of the emergency monitoring vehicles" during a nuclear submarine accident exercise.
Peter Burt, researcher at the anti-nuclear weapons pressure group Nuclear Information Service, said: "This is a worrying string of events in a short time at Devonport.
"If the site operators are not able to improve performance rapidly the MoD should take steps to take the operating contract away from Babcock."
Nuclear engineering consultant John Large, who has advised the government and environmental groups on nuclear issues, said: "These are not uncommon incidents in a complex operation like Devonport.
"But the level of detail is not good enough. For instance what is the connection with the torpedo tubes and a radiological incident on the submarine?"
The ONR declined to go into any more detail on the incidents, saying the reports were intended as summaries.
Babcock said in a statement: "Improvements relating to the ONR enforcement notice and other recently reported incidents at Devonport Royal Dockyard are being addressed through a broader nuclear safety improvement programme to further enhance our current high levels of safety, in agreement with ONR."
Plymouth City Council said it "takes the safety of nuclear operations at Devonport extremely seriously, as does the site operator.
"It is protocol that we are informed immediately of any safety issues or incidents that are likely to be of concern to the wider public.
"The operator also reports on its safety performance every six months at the local liaison committee."
The Ministry of Defence (MoD) declined to comment.
British and Irish Lions head coach Warren Gatland says he will not repeat Graham Henry's 2001 mistake by splitting the squad early in the tour.
[NEXT_CONCEPT]
Devonport naval base has been warned of legal action after a worker received a dose of radiation amid a series of safety breaches.