There are so many types of pre-schools... Montessori, Waldorf, Reggio, play based, developmental, ... What are they all and how do they differ?

There are many types of pre-schools. To name a few...

Play based pre-schools where there isn't any kind of official academic "pen and paper work", but concepts are taught through games, music, ....

Non-academic pre-schools where children DO NOT do any kind of academics at all and learn to work and play with others as well as following directions.
Academic pre-schools where children are taught in ways similar to elementary school.

Reggio-Emila programs where children choose which things they want to learn about and then the teachers design many lessons to teach them the concepts that they want to learn. The lessons come in many different modalities (art, music, movement...).

Waldorf pre-schools which focus on fantasy, and work to confirm the spirit in each child, his natural senses of gratitude, wonder, and reverence, while using natural materials (wood, metal, bees wax crayons...).

Summerhill preschools where children do whatever they want as long as they aren't hurting themselves, each other, or the materials. It is believed by the proponents of this philosophy that the children know what is best for them, or what they need to learn, and will naturally choose activities that they will learn what they need.

Montessori preschools which have many studies: practical life, sensorial, mathematics, language, science, cultural studies, fine arts... Each area has many different ways to teach each concept and children have the freedom to choose which way they learn the concepts.

Now, if all of this wasn't enough. There are schools that state they are of one philosophy and really aren't. So when choosing a pre-school you first need review all the different philosophies and figure out what it is that you really want from a pre-school. Once you know, look for programs in your area that fulfill these needs. Don't just look at the name, observe the school, make sure that they are following the philosophy they say they are. See which schools you like the best. Where do you feel most comfortable? Where does your child feel most comfortable? Talk to parents who have children in the school, and those who have children who have graduated from the school. Then make your decision.

By the way, there are some people who feel that they don't want their child to be "raised" by other people. I really understand this belief, but there are many pre-school programs that are only for a few hours a day and some that are only for a few days a week. (sorry, another choice). As an elementary school teacher I can tell you that NO MATTER how wonderful the parent is, there is a great difference between a child who has gone to pre-school and those who have not, and all research states that IN GENERAL, (there are ALWAYS exceptions), children who attend preschool do better academically and socially than children who do not.

For more information see - School Philosophies 101