Colour: The 5th is remarkably darker than the 7th, much more as the 5 additional years of maturation could explain. So most probably more refill casks on the 7th side.
Nose: The 5th is much more powerful and complex with lots of flavours that remind me of the Scottish countryside (the smell of cow stables, wet haystacks and wet sheperd dogs). And a quite dominant eucalyptus note besides dozens of other aromas. Contrary to this the 7th is much more simple mainly on a vanilla and almond profile rounded up with some exotic fruits. Clear winner is the 5th, but the 7th is on a high level too.
Mouthfeel: Both have a fat, oily and coating arrival on the palate with heavy peat notes on the 5th and almost no peat at all on the 7th side, but a very nice sweetness there. Both are quite punchy, I like that.
Taste: Again the 5th is much more complex with dozens of different flavours and aromas based on peat, marzipan, herbs and spices (vanilla is just marginal here). The 7th is based all around vanilla and fruity flavours (again almost no peat). Very different, but the 5th wins again.
Finish: Both are very long with advantages on the 5th side again due to the greater complexity. No drying or unpleasant woody notes in both.
So the clear winner is the 5th release mainly for its bigger complexity (yes, peat induces a lot of additional flavours and aromas over such a long time) without any sign of getting tired. Nevertheless the 7th profile is very nice too, but in a blind tasting you would not guess these two drams are from the same distillery and of a comparable age. Really interesting to see the difference peat makes...