Essentially there isn’t a difference between chips and chunks. After all they are basically the same thing. Chunks are simply bigger pieces of hardwood. The biggest difference is that chips burn faster than chunks. If you’re only going to be smoking your food for an average of 20 minutes, it would be fine to use a few cups of chips.
If however, you’re going to be smoking for an hour or more, it makes sense to use chunks. Remember, you don’t want to be opening the smoker to add chips every 20 minutes. Whether you’re using chips or chunks it’ll affect how often you add wood to your smoker.