The First Minister came under fire over the Labour UK Government's decision to step in to save Scunthorpe steelworks after failing to do the same in Port Talbot.
Eluned Morgan stressed the two steelworks were in different situations after UK ministers took control of the Chinese-owned British Steel site in Scunthorpe earlier this month.
Giving a statement on Tuesday, she told the Senedd: "The situation...was very different not only in terms of the global context but also...the relationship and intention of Tata Steel."
Baroness Morgan rejected "never credible" suggestions the Labour UK Government should have persuaded Tata to reopen a deal initially negotiated by Conservative ministers.
On calls to take control of the Port Talbot plant, the First Minister said: "That would have been unrealistic and unworkable because of the opposition from Tata."
'Legal conflict'
Baroness Morgan added: "It would have led to prolonged legal conflict with the company, to the possible accelerated shut down of the remaining blast furnace and Tata could have withdrawn its contribution of £700m to the construction of the electric arc furnace."
The Labour politician said construction of the electric arc furnace would begin this summer, with green steel set to provide a more sustainable and brighter future.
But Darren Millar, whose request for the Senedd to be recalled from Easter recess to discuss the issue was rejected, questioned the differing approaches in Wales and England.
The Welsh Conservative said: "People are upset, understandably, and furious about the fact there seems to be a completely different attitude towards Welsh steel."
He claimed Labour MPs "promised the earth" to steelworkers before last year's general election only to U-turn on pledges which turned out to be "complete works of fiction".
'Double standards'
Criticising "warm words" and the Welsh Government's "weak" strategy, Mr Millar warned Wales could miss out on a fair share from a £2.5bn fund for the steel sector.
Baroness Morgan replied: "I can't believe I'm getting lectures from the Tories, who had all the opportunities to step in – to do something constructive – and didn't."
The first minister claimed Tory UK ministers would not pick up the phone to her predecessor, saying she has pressed Labour colleagues to ringfence part of the £2.5bn fund for Wales.
Plaid Cymru leader Rhun ap Iorwerth criticised the first minister for "mocking" his party's calls for nationalisation of the Port Talbot steelworks.
"A pipedream she called it patronisingly, which has become something of a trade for this first minister," he said, accusing Labour of blatant double standards at Wales' expense.
'Betrayal'
Claiming Labour has abandoned workers, he told Senedd members: "After this betrayal, we need cast-iron assurances that the UK Government's investment in Scunthorpe in no way compromises the promises made to Port Talbot."
Baroness Morgan said: "It always fascinates me that nationalists want to nationalise but they want England to pay...this week, you want to nationalise steel, last week...Holyhead port."
Labour's Mike Hedges, a former steelworker, backed the first minister: "This is not a battle between Port Talbot and Scunthorpe even though some people are trying to make it such."
Welsh Lib Dem leader Jane Dodds said: "The UK's emergency action confirmed what many of us here in Wales had feared: that our workers are second-class citizens."
Baroness Morgan, who met steelworkers in Port Talbot on Friday, pledged to "move heaven and earth" to secure the future of Welsh steel through a "fair and just transition".

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