Different irons made by different manufacturers will have different lofts. Irons have evolved and become lower lofted as the years have passed.
The common loft for lower-lofted irons like a 3-iron or 4-iron is 20 degrees and 25 degrees. The average man can hit the 4-iron 170 yards and the average woman hits it around 120 yards.
2 irons are rarely sold in iron sets to the public due to the difficulty to hit and since they are being replaced by three and five woods and hybrids.
Middle irons such as seven irons are commonly found at 27 degrees. High-lofted irons such as 9-irons are typically lofted around 41 degrees.
Wedge lofts vary from 45 degrees (pitching wedge) to 60 degrees (lob wedge). Gap wedges and sand wedges are between usually found at around 52 and 56 degrees.
There are different sets of irons ranging from blades, player irons that are thin like blades but have a slight cavity, game improvement irons and super game improvement irons (massive cavity).
The order of those styles of irons are usually played by the lowest handicappers (blades) to the higher handicaps (game improvement irons).