I am new to QGIS, I have been using ArcGIS for most of my maps. I have two layers that are not overlapping properly. One is a shp file from a GIS clearinghouse and another from a delimited text source that I created myself. I am using the same CRS for the delimited text source as the shp file from the clearinghouse, and I checked "enable on the fly CRS transformation" to see if that would solve my problem as well.
With the coordinates you give, the dataset with (-73.230,40.333) is not NAD83 UTM 18N (which should be in metres), but rather NAD83 or WGS84 in degrees.
The second one looks more likely to be UTM coordinates in metres.
So what you have to do is set the CRS for the first layer with rightclick
-> Set CRS for layer to
EPSG:4326, and both layers should overlap.
This is what I get from your coordinates: