What makes a good golf club?
Lots of people choose the clubs they think are the best based on which have the highest price tag. Yes I will admit that the more expensive clubs tend to look fantastic and have lots of great technology in them, but just because they look good it doesn’t mean they are right for you.
The best irons now have a cavity back design, which means they have more metal around the edge of the head at the back, then a lump of metal right at the bottom with a cavity in between that and the face. The metal they add to the edges helps to stop the head twisting when you hit the ball, giving it a larger sweetspot, and the metal right at the bottom helps you to get height on your shot for added accuracy. So in terms of irons then there are no massive differences to set them apart.
Yet with drivers then the manufacturers have a lot more room to play around with them and suddenly you find them coming out with all sorts of crazy technology to help your game. The square driver is an example of this innovation, by adding extra weight and support to the corners of the head, which gives it that square shape at address, then they have massively increased the MOI and therefore the size of the sweetspot. Or you have adjustable drivers with weights you can shift around to help combat that vicious hook or slice you suffer with, there are even ones with two faces (one inside the head) to help your shot.