Envoys at talks aimed at ending North Korea's nuclear programme will discuss a "roadmap" for disabling its nuclear facilities, a US official said.
Mr Hill said differences remained on the issue of disabling
Negotiators from six countries would study a draft text setting out targets to be achieved over the next months, US negotiator Christopher Hill said.
But he said differences remained between the parties, including over what "disabling" means in practice.
Pyongyang agreed in February to end its nuclear programme in return for aid.
It has already shut down its main nuclear reactor at Yongbyon, in return for shipments of fuel oil.
Officials from the six countries involved in the talks - the two Koreas, China, Japan, Russia and the US - are now trying to pin down details of the second phase of the deal, under which Pyongyang must disclose and disable all of its nuclear facilities.
The talks, taking place in the Chinese capital, Beijing, began on Thursday and are due to end on Sunday.
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Heading into day two of the talks, Mr Hill told journalists that the idea was "to lay out a road map until the end of the year".
He said that North Korea had agreed to some measures but more work was needed.
"The DPRK (North Korea) has agreed to some steps and I think we've looked at what they've agreed to and, frankly, we'd like more and they'd like less and let's see what we end up with," he said.
There was no agreement on what constituted disabling yet, he said.
"For disabling to be meaningful, it has to involve a concept of it being difficult for the DPRK to reconstitute its nuclear programmes," Mr Hill said.
The South Korean negotiator, Chun Yung-woo, said that the differences were not insurmountable.
"They are not differences we can't overcome, because we have the political will to reach such an agreement," he said.
North Korea tested its first nuclear device in October 2006.