What is difference between 'g' and 'G'

What is difference between ‘g’ and ‘G’

G stands for Newton’s universal gravitational constant, whereas g stands for the acceleration due to gravity at a certain point.
G = 6.67300 × 10-11 N.m2.kg-2, G is a constant throughout space and time and it is a scalar quantity.
g = 9.8 m.s-2, g is acceleration due to gravity which is a variable quantity and a vector qualtity.

According to Newton’s law of universal gravitation the force of attraction between two bodies is given by
F = GMm/r2 ---------- (i)

From Newton’s second law of motion the weight of a body of mass m is

F = mg -----------------(ii)

From (i) and (ii)
mg = GMm/r2
g = GM/r2

g is a constant at a given location, which depends upon M and r.