Is spinach the same as pechay?

No, spinach and pechay (also known as bok choy) are not the same. Spinach (Spinacia oleracea) is a leafy green vegetable with tender, dark green leaves, while pechay (Brassica rapa subsp. chinensis) is a type of Chinese cabbage with a thicker, white stem and dark green leaves. They have different flavors, textures, and culinary uses, although both are nutritious leafy greens.