Here's the basic process details. Note that there are several other variations to this (and shortcuts), but this will the job done:
1. Set up your symbology with the unique values in one feature class
2. Once it looks good, in ArcMap, right-click on the feature class and choose "Save as Layer File..."
3. Save it to a location where you can find it again.
4. Add in to ArcMap your other feature class you want symbolized the same way.
5. Right-click on this feature class, Properties, then choose the "Symbology" tab.
6. On the left, under "Show:" make sure the proper method is hightlighted. I'm guessing with your data it shoudl be set to "Categories, Unique values", but it will depend on your data and how you are symbolizing it.
7. Then click on the "Import..." button in the upper right. Change the radio button to "Import symbology definition from another layer in the map or from a layer file:"
8. Browse to your layer file
9. When the "Import Symbology Matching Dialog" window comes up, be sure to fill in the "Value Field" so it matches the field you used when creating the symbology (i.e. the unique values field).
10. You should be all set.
Layer file creation:
ArcGIS Help (10.2, 10.2.1, and 10.2.2)
Importing symbology from another layer:
ArcGIS Help (10.2, 10.2.1, and 10.2.2)
Chris Donohue, GISP
