A system of equations can intersect at no points; this is when the lines are parallel, which means they have the same slope and different y-intercept.
A system of equations can intersect at one point; this is when the lines have different slopes.
A system of equations can intersect in infinitely many points; this is when the graphs overlay one another, which means they are graphs of the same line. The two equations would equal the same thing.
The relationship between the 7's is not different in any way because the sevens are all in the same place. The sevens are in the hundreds and thousands place.