How do trains make turns if their wheels spin at the same speed on both sides?

As others have stated, some trains have a conical shape to the wheels that lets them rotate at different speeds. Others don't, and the wheels slide/slip creating a deafening screeching sound. It's especially loud when the train is travelling uphill and needs to exert a lot of force on the wheels.
Source: am locomotive engineer

two videos here which are highly agreed as simple and good answers.