How would i know if I have a reverse 1938? Probably a little to late knowing, there beat up. Here are 2 1938 nickels found coin roll hunting last couple months
The photo and description posted by @2manyhobbies is good. A few years ago @Lehigh96 posted a really excellent article on the differences between the two steps. Hopefully he can link it for you in this thread. Essentially, the steps of 38 look like someone drew them freehand and on the steps of 39 it looks like someone drew them using a ruler.