By and large, (and you can never keep up with the development of these things) golf clubs split into three categories:
'Woods' (which used to be made out of wood, but are now made out of the metals and alloys) which are used to hit the ball the longest distance. 'Irons' which are used to hit the ball over long or short distances, depending on the degree of loft on the clubhead. Putters, which are used to delicately roll the ball into the hole once a player has reached the green.
The significant differences between the types of clubs are the length and the degree of loft on the club head.
Woods are the longest clubs, as the length of the club allows a greater transfer of power to the ball.
They are for the big shot off the tee ' and off the grass when the ball lies cleanly ' but they are 'distance' clubs, rather than 'control' clubs. The degree of loft (the angle of the club face that hits the ball) is more limited on woods than the degree of loft on irons. The greater the degree of loft, the higher the ball should rise.
Irons have widely differing degrees of loft. If the face has little loft, (a one-iron is almost flat) the ball will travel a long distance. If the club has high loft (a pitching wedge is steeply angled) the ball will travel a shorter distance but fly high into the air. This allows the golfer to have more control. If you hit something low and flat it will bounce forward over a considerable distance. If you hit is steeply up into the air it will stop almost dead when it lands (which is what you want when aiming at the green).
Putters have completely flat face because all they have to do is make the ball roll gently along the ground in the direction of the hole.
The performance of the club should be consistent. The performance of the golfer is the hard bit.