The two laws
Two laws describe how light travels when it is refracted.
First law
The incident ray, the refracted ray and the normal at the point of incidence all lie in the same plane.
Second law — Snell's law
For light passing from one medium into another, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant that depends only on the two media.
That constant is called the refractive index of the second medium relative to the first.
Same plane in both laws
The first law of refraction is worded like the first law of reflection: the rays and the normal lie in one plane. What differs is the second law.