I know that lemon blossoms are used in foods, but I have only witnessed them as a decoration on cakes or pies and various pastries. I believe Greek foods often find lemon blossoms in the ingredients, but I may be incorrect on that. Somewhere, my grandmother recorded a recipe for lemon blossom preserves, and I'll try and dig it out for you, if you would wish.
I am incapable of offering a comparison in tastes between Lemon and Orange Blossoms.
Flower blossoms, as an ingredient, are used frequently in cooking in jams and jellies, baked goods, pies and pastries and soups to name a few. The concern is to find blossoms that are free of pesticides and other chemicals. Once found, the petals are used almost exclusively. And obvious exception to that would be rose hips...and I'll be making jelly from those right after the first frost. Another would be candied, where the entire blossom is "painted" thoroughly with egg whites and thoroughly coated with superfine sugar, then allowed to dry completely (several hours).
I know a couple of people who mix stock petals and nasturtium petals or even chrysanthemum petals in their salads.
Hopefully, all will confirm first whether a flower is poisonous before ingesting....
Pain is inevitable. Suffering is Optional.