Dry vs Wet Measuring Cups

What is the difference between dry and wet measuring cups?

I have always wondered what the difference is between a dry and a wet measuring cup.  Here's what I found on the web.

You can use a dry cup to measure liquid but it may not be accurate because you fill the cup to the very brim and that will cause some liquid to spill out when you move the cup and you won't have an accurate amount.  Also, it would be very hard to pour since there is no spout.

You cannot use a liquid cup to measure dry ingredients.  The reason is you have to  'eye' through the glass to see how much you put in it and if you tap the glass to level it out you compact the ingredient and might end up with more volume than what the recipe calls for.

So for dry ingredients use a dry measuring cup.  Fill it to the top and level it with a knife and you will have the correct amount the recipe calls for.

For liquid ingredients use the wet measuring cup and you will be able to pour it without spilling.  You will also be able to measure in ounces if needed.

Some sites recommended using a scale to weigh dry ingredients but that sounds way too complicated to me.  The scale would be used mostly if you are baking.