The main difference between an aluminum sole plate and a stainless steel sole plate is that aluminum sole plates are more prone to stick to clothes as you iron. This is undesirable because it has the potential to damage your clothes. However, even apart from this danger, the sticky performance of irons with aluminum sole plates results in a more difficult ironing process. Irons with a stainless steel sole plate, on the other hand, are all considered non-stick, are better at avoiding damage to clothes, and provide a smoother ironing experience.
One advantage irons with aluminum sole plates have over those with stainless steel sole plates is that aluminum sole plates are better at evenly distributing heat across garments. This makes it easier to rid garments of wrinkles quickly without having to go over an area several times.
Another advantage associated with irons with aluminum sole plates is their cost. Irons with aluminum sole plates are typically cheaper than those with stainless steel sole plates.
Besides the type of material used to construct the iron, the other specification that determines how well the iron will perform is the number of holes it has. The number of holes differs from manufacturer to manufacturer and has nothing to do with its composite material. This means, all other things being equal, that aluminum, stainless steel and ceramic irons perform equally well in this department.