i ++ given ++ i

When used alone as a sentence, there is no difference, i.e., when there is a semicolon, no difference.

When used in an expression,

Such as:

a = 10;

b = a++;

I.e., b is 10, but after a plus one.

a = 10;

b = ++a;

I.e., a first add a, then b = 11.