1. How big is the purchase, that is to say, how big is the maximum usable electric drill, the bigger, of course, the more expensive. In my personal sense, the maximum 20 mm drill is enough for household use. The biggest one I bought is 16 mm.
2. In the same model, there are some additional functions. For example, the R indicates that the drill bit can be reversed. This has the advantage that when you use the positive drill, you can use the reverse to try again. As far as my experience is concerned, it is very useful. The E indicates that the electric drill in the model can adjust the speed. Of course, the E indicates that the electric drill can adjust the speed. It's also good to use low-speed operation when you don't need such high speed. Of course, with these two functions, the price will be higher. Whether you choose or not depends on your choice.
3. In the case of insufficient budget, choose the right price.