A green tile can feel completely different depending on what happens on its surface. The Emerald gloss has a strong reflective quality, so the colour picks up highlights and appears deeper as the light moves across the wall. Crackle Green has a more artisanal visual character, with the crackled surface introducing another layer of detail.
White is a useful comparison because the colour stays the same while the finish changes. Matt White gives you a softer, more restrained wall, whereas Gloss White reflects more of the surrounding room and feels brighter.
It is a good reminder that choosing a tile is not simply about picking a colour from a screen. The relationship between colour, finish and light can alter the way that colour actually feels once it's on the wall.