An analysis of secondary school reports published by the Office for Standards in Education reveals comments on the sixth form may be a few phrases tacked on to details on the rest of the school.
The research, based on a sample of 35 reports, was commissioned by the Sixth Form Colleges Association, which is demanding parity in inspection and funding between colleges and schools.
The association claims the two sectors are being forced to compete for students, yet are not on a level playing field where parents and students get the same amount of information on both.
Terry Melia, chief inspector at the Further Education Funding Council, backed the colleges' case, saying providers of post-16 education and training should have common inspection arrangements.
"Basically we could work to any framework agreed by the FEFC and OFSTED, " he said. "I think this is certainly an issue for review."
Change might begin with the creation of a separate section for comments on sixth forms in OFSTED reports, he added.
The association's study found school reports lacked detailed statistics on sixth forms and were inconsistent in comments on class size, student-teacher ratios, retention rates and student support. Inspectors differed on what constitutes too small an A-level class. Examples ranged from classes of one to six.
Broad estimates of retention rates made by the researchers suggest losses in some of the sample which would result in severe financial penalties in the FE sector.
At recently-inspected Winstanley College, Wigan, principal Dennis Lavelle said schools should be as accountable as colleges. Now that the Government was encouraging schools through its competitiveness drive to open new sixth forms, the public should be assured they gave value for money.
Barry Hicks, vice-principal of St Vincent's College, in Gosport, Hampshire, where a local school has recently won permission to open a sixth form, said: "Clearly if local parents and students are to make choices then they have got to have free access to information."
But an OFSTED spokesman said schools were inspected as rigorously as colleges. Detailed statistics which did not appear in OFSTED reports were nevertheless supplied by schools to the Department for Education and Employment.
The spokesman said the work of the inspectorate was not confined to single-school inspections, but included reports focusing on individual issues. A study to be published shortly after Christmas brings together examples of good practice in school sixth forms.
* Ministers warned colleges against complacency this week despite figures in the Further Education Funding Council annual report which show an 11 per cent efficiency gain and 5 per cent growth in student numbers last year.
Their comments were echoed by Terry Melia, FEFC chief inspector, in his annual inspection report this week which was leaked to FE Focus in September (TES September 22).