Latvian spruce has short, sharp, dark green needles. Spruces are shaped and dense. It has a pleasant aroma. A cut Latvian spruce lasts ~7-10 days indoors, ~2-2.5 weeks in a pot. After that the needles fall off quickly.
Nordmann fir has long, soft, flat needles - vibrant green on top and silvery underneath. The long needles and thick branches make the fir particularly stout. The fir does not have a strong aroma. A cut Nordmann fir will last ~2-2.5 weeks indoors, ~3-4 weeks in a pot. After that, the fir begins to wilt - needles and branches go down.
Blue spruce has a medium-long, very sharp needle. The color of the needles can vary from greenish to greyish. The spruces are shaped and thick. It can have an unpleasant smell, especially after changes in temperature and when touched (e.g. when brought indoors). The cut blue spruce lasts ~7-10 days indoors, ~2-2.5 weeks in a pot. After that, the needles fall off quickly.