I am no expert, far from it...
But, I sent my perscriptions into CAA Gatwick and they gave me a partial thumbs up, based on the data. They said, it will depend on if i can read a particual specified line on the chart with my glasses on...
My perscription is +4.25 and +4.75, so right on the border of +5, combined 20/20 and indivudual no less that 20/30.
There is a different, but i was aware it was -/+2 difference max?
As i say, i am no expert, and not 100% sure.
Think it might be astigmatism thats -/+ 2 difference on second thoughts