Thanks for sharing InformationI agree with Subhotosh. Pre-Algebra topics can differ, from school to school.
For me, Pre-Algebra was taught after Arithmetic and before Beginning Algebra. It covered topics like signed numbers (and the rules for doing arithmetic with them), the concept of using symbols to represent unknown numbers, and some simple formulas for working with geometric shapes. The course included introductions to additional subsets of the Real numbers (eg: Integers, Irrational Numbers), and it re-introduced the Real Number Line as a visual aid. My instructor liked to remind us that the Real number line is "dense", although I didn't really comprehend the importance of that until much later. They mentioned some basic properties, like association and distribution, but we didn't practice that much. My Pre-Algebra also covered simple square roots and powers; we learned how to simplify basic square-root expressions. We learned about prime numbers and how to write the prime factorization of Natural numbers. I remember the course finished by introducing the XY-coordinate system, for locating points on a surface. We did plot some points (that was the first time I saw graph paper), but it was just as much about proper labeling and vocabulary.
Beginning Algebra began with linear polynomials, simple factoring and distribution, and solving simple linear equations ("What you do to one side of an equation, you must always do to the other side!", eh.) We were also graphing a LOT of lines, right away.