I'm trying to decide whether there's a size discrepancy. I can't figure out what the light blue data is supposed to represent! If there is a size discrepancy, the data that says it's using UTM 17N may really be in a UTM zone that's using feet, or a state plane zone in feet.
A trick is to identify which layer is definitely not in the right plane. Remove its coordinate system (set to unknown or 'clear' depending on ArcGIS version). Now add it to ArcMap with the other data. Set the data frame's coordinate system to other possibilities like UTM 18N, the various state plane zones, etc. If you can get the other data to line up with the 'unknown' one, you've just identified its coordinate system.
Post the extents of the datasets if you can't figure it out.
Melita