
Both these rules are to find the direction of force on a moving charge in a magnetic field.
1. Flemings left hand rule- Strech the thumb and the first two fingers of the left hand mutually perpendicular to each other.If the forefinger points in the direction of magnetic field, central finger in direction of current then the thumb gives the direction of the force on the charged particle.
2. Right hand rule- Open the right hand and place it so that tips of the fingers point in the direction of magnetic field and thumb in the direction of current then the palm faces towards the force.