Sapphire and Lapis Lazuli are completely different stones.
- Sapphire comes in transparent to opaque while Lapis Lazuli mostly comes in opaque.
- Sapphire chemical composition is different than Lapis Lazuli.
- Sapphire comes in many colors like: green, pinkish orange, pink, white, yellow, etc. but Lapis Lazuli comes in blue, greenish blue or purple blue color.
- Lapis Lazuli is a mixture of several minerals that’s why it’s a rock; while Sapphire is not a rock.
- Both of them appears different visually.
- You can find more details at http://www.gemstonebuzz.com/lapis-lazuli and http://www.gemstonebuzz.com/sapphire
Hope this helps you.