Step 1: Compare the two equations.
The given lines are:
\[
2x + 3y - 9 = 0 \quad \text{(Equation 1)}
\]
\[
4x + 6y - 18 = 0 \quad \text{(Equation 2)}
\]
Step 2: Simplify Equation 2.
Observe that Equation 2 is a multiple of Equation 1. We can write Equation 2 as:
\[
4x + 6y - 18 = 2(2x + 3y - 9)
\]
This shows that Equation 2 is simply twice of Equation 1, meaning both lines are the same.
Step 3: Conclusion.
Since the two equations represent the same line, the lines are coinciding lines.