To find the difference between the areas of Hawaii and Rhode Island, we first express both areas in scientific notation:
- Hawaii: \( 2.83 \times 10^4 \) square kilometers
- Rhode Island: \( 4 \times 10^3 \) square kilometers
Next, we need to align the powers of 10 before subtracting the areas. We can convert the area of Rhode Island to match the power of 10 used for Hawaii:
\[ 4 \times 10^3 = 0.4 \times 10^4 \]
Now both areas are in terms of \( 10^4 \):
- Hawaii: \( 2.83 \times 10^4 \)
- Rhode Island: \( 0.4 \times 10^4 \)
Now we can subtract the two areas:
\[ 2.83 \times 10^4 - 0.4 \times 10^4 = (2.83 - 0.4) \times 10^4 = 2.43 \times 10^4 \]
Thus, the difference between the areas of Hawaii and Rhode Island, expressed in scientific notation, is:
\[ \boxed{2.43 \times 10^4} \text{ square kilometers} \]