Lp and lpr postscript

I recently created a wireless print server with cups and samba on raspbian. I'm able to print from every device on my home network but I noticed a strange behaviour: when I print a postscript file directly from the raspberry pi lp works perfectly, while lpr prints a lot of sheets, the majority blank, some with random lines. Has someone experienced the same? Can someone give me or point me to a clear explanation about how gs, lp, lpr and cups interoperate?