Program for a speed camera
Not much to say I think, but here goes:


You're using clear, descriptive variable names, which is good. Such names make code easier to understand, which is especially important when you're working on large, complex projects.
Calculating the number of demerit points can be simplified to int demeritPoints = speedDifference / 5;.
Your code always displays the demerit points and suspension message, but from the requirements it looks like it should only do so when the speed exceeds the limit.
Instead of writing "SPEED LIMIT : " + speedLimit, you can use an interpolated string: $"SPEED LIMIT: {speedLimit}", which makes formatting a little easier.