Malt Yield

[Galena]

I am just putting a recipe together for tomorrow in Brewfather and originally put Crisp Maris Otter in as my base malt, since then I bought Muntons MO and on replacing the Crisp with the Muntons there is a large difference in yield. Crisp comes up as 82.5% whilst Muntons is 78.26% and this is throwing my recipe out by quite a lot.
Is this a realistic difference, not sure where to check?