Alongside the camera, it is often quite clear what has been removed to save money. The screen and battery are not what companies are saving money on. In fact, quite a few medium class mobile phones have really good ones. The processor also tends to keep up very well, even though it is a little slower than the top models. Today, we rarely have any problems with the amount of storage space on our phones.
However, you will quickly notice a lack of protection against dust and water: The IP rating. Labelling costs money, and often savings are made there – the phone is called “splash proof” without further details. Wireless charging is also a luxury feature that quickly disappears... and that you actually can live without. Speaking of charging, cheaper phones usually don't have the same kind of fast charging as the more expensive models.