Both drams are typical Lagavulin and very enjoyable with different spikes: The 2017 is more balanced and smoother while the 2018 is more spiked and wild - there is a one points difference between the two in my book what is a draw, actually! Nevertheless I like the new "Distillery Exclusive" (WB id 98058) bottling much better, honestly...
The 2017 is one shade darker at pale gold than the 2018 which is at pale straw. The nose is very comparable at the first sniff with slightly more wooden notes in the 2017 and more peaty-ashy aromas in the 2018's nose. Both are pretty fine with a minor (one points) advantage to the 2018.
The 2017's palate is rich, bold and quite complex - pretty good by Lagavulin standards I would say. All there that one would expect, no flaw or off-note at all. The 2018 is a little sweeter but a little more bitter too - actually I like the 2017 better than this year's edition on the palate (by two points). Some water really improves the 2017 both in the nose and taste while the 2018 profits less from a reduction (the bitter notes increase in sync with the pleasant ones, so actually it stays in the same balance).
The 2017 arrives bold, a little hot and instantly coating on palate while the 2018 does … the same, actually. Maybe the 2018 is a little bolder but it owns a slightly bitter-astringent moment too (that is not with the 2017). The 2017 finishes very long, more spicy and without any distracting moment - actually this is the best about this dram. The finish of the 2018 is a little shorter (not much, almost of the same length) but very bitter-drying on cold ashes, tannins and cold metals. If you prefer the extremes the 2018 is for you, but honestly I prefer the 2017 over that (one point).