The Coalition is offering minimum download speeds of 25 megabits-per-second (Mbps) by the end of its first term in 2016 if it wins government from Labor this year.
While this is slower than the minimum 100Mbps being offered under Labor's NBN project, Abbott argued that the Coalition's plan would be better and cheaper to deliver.
It wants to use technology — which Communications Minister Stephen Conroy has labelled "second rate" — that runs fibre optic cable to the node, or boxes on street corners.
This means that the final connection to a home would be through Telstra's existing copper network, rather than through a fibre optic cable all the way to the premise, as the government is doing.
"We will build fibre to the node, and that eliminates two thirds of the cost," Abbott told reporters in Sydney on Tuesday.
But Minister of Infrastructure Anthony Albanese said that this would be a disaster because, unlike the government's fibre-to-the-premise technology, it couldn't be easily upgraded.
"This policy ... for most cases, won't result in any higher speeds being delivered," he told reporters in Canberra.
Federal independent MP Tony Windsor agreed.
"The 'full-strength' NBN will better enable technologies and services that haven't even been thought of to be delivered," he said in a statement.
The Coalition puts the capital cost of its plan at AU$20.4 billion against Labor's AU$37.4 billion.
Including funding, the cost rises to AU$29.5 billion against AU$44.1 billion under the project being overseen by the government-owned NBN Co.
Queried about the 25Mbps minimum speed for households, Opposition Communications Minister Malcolm Turnbull said that broadband utility flattened out in a residential environment.
Abbott said 25Mbps would be enough for home usage, adding that at this speed, a family of four could simultaneously download four different sport or movie programs.
"We are absolutely confident 25 megs is going to be enough — more than enough — for the average household," he said.
While the Coalition is offering only fibre-to-the-node services for most households, high-end users like hospitals, educational centres, and new housing estates would get connections to premises.
"It's very flexible," Turnbull said of the policy.
Australian Greens Leader Christine Milne said that the concept of installing tens of thousands of boxes on street corners meant most households would be "stranded" on a decaying copper network while new housing estates would get modern fibre technology.
"It's a farce," she said in Hobart.
If the Coalition won a second term, the minimum speed would increase to 50Mbps for the vast majority of households.
"I am confident that it gives Australians what they need," Abbott said.
Under the Coalition's plan, the NBN rollout would be completed by the end of 2019 instead of the current deadline of 2021, with priority given to areas that are most underserviced.