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There are different levels of Diploma, which are graded like this:

• Foundation Diplomas are at Level 1 – they take about the same time to do as 4 or 5 GCSEs, and are worth the same as 5 GCSEs at grades D–G
• Higher Diplomas (Level 2) – take about the same time to do as 5 or 6 GCSEs, and are worth 7 GCSEs A*–C
• Advanced Diplomas (Level 3) – take about the same time to do as 3 A levels, and are worth 3½ A levels
• Progression Diplomas (also Level 3) – take about the same time to do as 2 A levels and are designed for those who can't complete a whole Advanced Diploma.
  

Foundation and Higher Diplomas are there for anyone aged 14–19; you can only start Advanced and Progression Diplomas if you're 16 or over.

You can take a Diploma at one level and then progress to the next level up when you're done – for example, take a Higher Diploma when you're doing your GCSEs, then do an Advanced Diploma in Years 12 and 13.