Step 1: Calculate the area of the 34-inch television.
The area of a square is given by \( A = \text{side}^2 \). The diagonal of a square relates to its side by the Pythagorean theorem:
\[
\text{diagonal} = \text{side} \times \sqrt{2}.
\]
For the 34-inch diagonal, the side length is:
\[
\text{side} = \frac{34}{\sqrt{2}} \approx 24.04 \, \text{inches}.
\]
Thus, the area of the 34-inch square television is:
\[
A_{34} = 24.04^2 \approx 578.92 \, \text{square inches}.
\]
Step 2: Calculate the area of the 27-inch television.
For the 27-inch diagonal, the side length is:
\[
\text{side} = \frac{27}{\sqrt{2}} \approx 19.09 \, \text{inches}.
\]
Thus, the area of the 27-inch square television is:
\[
A_{27} = 19.09^2 \approx 364.42 \, \text{square inches}.
\]
Step 3: Calculate the difference in areas.
The difference in area between the 34-inch and 27-inch televisions is:
\[
\text{Difference} = 578.92 - 364.42 = 213.5 \, \text{square inches}.
\]
Step 4: Conclusion.
Thus, the difference in the areas of the two televisions is 213.5 square inches. The correct answer is (B) 213.5.