Post-devolution investment in secondary education has had disappointing results, a major review reported this week.
The Nuffield review of 14-19 education in England and Wales - the largest report of its kind for 50 years - applauds Wales's "inspiring vision" and "distinctive" policies.
It also suggests England could learn lessons from some of Wales's more successful policies since 1999.
But the report says Wales still compares badly with England in its GCSE results and in the number of youngsters not in education, employment or training (Neets). It concludes: "There is not the progress one might expect from so much investment."
Education experts and teachers' unions called this week for more investment and better leadership to address the criticisms in the report.
Professor Gareth Rees of Cardiff University, one of its authors, said: "We have a very exciting policy agenda in Wales that goes a long way to meeting some of the recommendations, but there are problems in terms of attainment and investment levels.
"The Assembly government will have to grasp the nettle on funding in order to bring about a fully effective collaborative system."
Gareth Jones, secretary of the heads' union ASCL Cymru, welcomed the report, but said it needed to be seen in the context of the funding gap between Wales and England. "We would achieve a great deal more in 14-19 education with more funding," he said.
The report, which has taken six years to complete, highlights the "distinctive programmes" undertaken by the government, such as the vocationally led learning pathways, which it says gives a "broader vision of learning and wellbeing".
By contrast, the report describes arrangements for 14 to 19-year-olds in England as complex and having resulted in "fragile" collaboration. It says England should build on the "highly successful" collaborations developing in Wales and suggests that the Welsh baccalaureate could be used as the model for a new qualification in England.
Since devolution, the report says, the Assembly government "would appear to show greater respect for the professional judgment of teachers than is the case in England".
Teachers in Wales also feel far less constrained by "constant interventions" from government and the assessment regime.
The report praises both Wales's learning and skills measure, which forces collaboration between schools and colleges, and its post-16 transformation agenda, which aims to improve basic skills and cut the number of Neets, as "imaginative" attempts to address future needs.
But there are many difficulties to overcome, the report warns, particularly in rural areas, where learning networks struggle to provide a wide choice of courses, and in deprived areas where education has traditionally failed to make a difference.
The report makes 31 recommendations for both countries to follow.
An Assembly government spokesman said: "We're pleased the review recognises the significant post-devolution developments taking place in education in Wales, which the authors note policymakers in England may want to consider . We will need time to consider the . recommendations to see how they might support the development of policies in Wales."
David Egan, professor of education at the University of Wales Institute, Cardiff, said: "I don't think it's unfair to say outcomes have been disappointing, but there has been more progress than they recognise. We need stronger leadership to take forward the good stuff."
Gary Brace, chair of the General Teaching Council for Wales and a member of the review's advisory panel, said Wales came out well in the report, but he added: "The review points out the difficulties and challenges to be overcome if Wales is to cease comparing unfavourably with our European neighbours."