Plant foods are definitely different from animal foods when it comes to their iron content. In animal foods, iron is often attached to proteins called heme proteins, and referred to as heme iron. In plant foods, iron is not attached to heme proteins and is classified as non-heme iron. Heme iron is typically absorbed at a rate of 7-35%. Non-heme iron is typically absorbed at a rate of 2-20%.
You can see that even though there is better overall absorption of heme iron, there is also a fairly large range for absorption regardless of the iron form involved. This absorption range is large because iron absorption is influenced by many different factors. For example, our bodies absorb more iron when we are iron deficient, and they cut back on iron absorption when plenty of iron is already available. Dietary factors are among the many factors that affect iron absorption. However, dietary factors appear to play a greater role in non-heme iron absorption from plant foods than they do in heme iron absorption from animal foods.