It would depend on the recipe.

Coriander is the whole plant, whereas cilantro is a stage of growth: the stage producing light green broad-leaf growth prior to bolting.

Bolting is the next stage of growth, in which coriander flowers and produces seed. The plant becomes long and spindly. Leaf growth is sparse, finer and darker in colour. Stems are darker in overall colour with fine light/dark striation along the axis of growth. Once the plant has bolted, it takes on a bitter taste and is no longer suitable for recipes calling for coriander.

Misuse of the term cilantro as a name for the plant is largely confined to the United States, and this often confuses Americans who think they are supposed to use the spice made from the ground seed when in fact chopped leaf is indicated. In the rest of the world, "coriander" customarily refers to the entire plant (root leaf and stem) in the cilantro stage, and "coriander seed" indicates, well, coriander seed.

Coriander is a pungent flat leaf herb, part of the carrot family, and is very similar by eye to flat leaf parsley. Dried Coriander leaf is much less tasty.

When making salsa, parsley can provide similar texture, and pepper the spicy flavor.

Coriander tastes nothing like cilantro, even though they are from the same plant. I use both coriander and cilantro quite often so I can say this with certainty. Coriander has a mild floral flavor, like a cross between citrus and sage. I would try a combination of sage and lemon zest.